Point 1: Likely what you want to learn you can
learn well without going back to school. Indeed, at
a high end research university, it is in effect or
explicitly assumed that you can teach yourself.

If you are in software, then likely you are heavily
self-taught. Well, being self-taught in nearly all
parts of academic engineering is easier than in
practical software if only because in nearly all of
academic engineering the learning materials are
much, much better written.

To do self-study in academic engineering, it is
crucial to get some of the best materials, usually,
still, textbooks. For this, investigate and pick
carefully. Indeed, you should have little trouble
finding what the favorite textbooks are for what you
want to learn -- likely can get enough just by going
to the Web sites of the most relevant universities,
departments, courses, and professors. For the
engineering schools, don't be reluctant to go right
to the top -- MIT, Cornell, CMU, Georgia Tech,
Stanford.

If you need more, then maybe send a nice e-mail to
some professors, in a few words explain your
situation, maybe include a list of the candidate
books you have found, and ask for suggestions, say,
the textbooks he's been using, on the list or off.

Point 2. If you want an 'expensive' Bachelor's
degree, say, for $50,000 a year at an Ivy League
university, instead shoot for a Masters or better
yet a Ph.D. from such a school. Why? In important
ways, the graduate degree is faster, easier, and
cheaper than the Bachelor's. In my experience, at
the best schools, Ph.D. students rarely pay tuition
anyway. And from the famous Ivy League schools,
it's generally easier to get accepted for a Ph.D.
than for a Bachelors.

Point 3: If you want a Bachelor's degree or need
one (say, to get accepted for a Master's or Ph.D.),
then one option is just go to about the cheapest
school you can, maybe starting with just a two year
community college and then transferring to a four
year college to finish your Bachelor's. "Don't pay
a lot for this muffler" -- uh, Bachelor's degree.
Everyone in higher education understands that there
are good students with little money or family
background in academics and respect such students.
If you learned well, then as you finish your
Bachelor's you can get some high GRE scores which
will look great applying to a Ph.D. program and make
up for starting at a community college.

Point 4. Even following Point 3, to save money and
get better results, still emphasize self-study.
That is, before taking the course, study the course
on your own first. Then take the course, lead the
class, ace the course, amaze the professor, and get
glowing recommendations, say, to a good four year
college for your last two years, or from a four year
college to a Ph.D. program, as the best student he
ever had, maybe get a scholarship. Besides, this
way might get to take extra courses at once, save
tuition money, time on campus, and expenses
commuting to campus and look still smarter, all
because you just studied the material before you
took the course.

Of course, this self-study stuff can work great for
the more theoretical and mathematical parts of
engineering but work less well where you might need
time in an expensive lab. So, emphasize the
theoretical and mathematical parts and for the rest
do what you can without a lab. Then in school, when
you take the lab course, you still have a head
start.

E.g., on self-study, I got a Ph.D. in essentially
applied math, but I never really took freshman
calculus. Instead, in my freshman year the poor
school I was at insisted I take some 'college
algebra' which was beneath what I'd covered in four
years of math at a relatively good public high
school. So, not to fall behind, I got a decent
calculus book and dug in. For my sophomore year, I
went to a much better college and started on their
sophomore calculus (right, never got course credit
for freshman calculus), was likely the best student
in the class, was a math major, wrote an honors
paper on group representations, and got 800 on the
Math knowledge GRE.

So, I covered freshman calculus well just on my own
from just a calculus book. You can too. Indeed, if
you take a calculus course, mostly you learn from
the book anyway.

Just study the material from the book before the
course instead of mostly from the book (which
usually you have to do anyway) during the course.
If you get hung up, then ask for some help, on-line,
from some videos (if they help -- not all of them
are good), knock on the door of a prof and ask a
question, etc. Tell him you are studying on your
own and want to be clear on, say,

f'(x) = lim (f(x + h) - f(x))/h
h --> 0

or some such. Mostly a prof's office hours are not
very busy, and a prof might answer one good question
for you even if you are not in such a class or even
in his school. If he refuses, then to heck with
him!

There are some poor textbooks out there, and some of
the better books will still have a poor chapter or
two. A bad book or chapter can be a chuckhole in
the road but only if you let it. If some material
seems not well written, like drilling through
bedrock, or needing prerequisites you don't have,
then get 1-3 alternate sources, maybe just by
photocopying some chapters from some books in a
library or buying some books as supplements. E.g.,
there is a book on linear algebra by E. Nearing, and
it quite good except it has a chapter in an appendix
on linear programming that is just awful. Nearing
understood a lot of linear algebra but not linear
programming!

So, get copies of, say, the three best books. Learn
mostly from the best book and use the other two for
alternate explanations (so that you won't get stuck
and won't misunderstand).

Now, textbooks are darned expensive, the latest
editions, in hardcover, commonly over $100 a copy.
Three such books could set you back $300 -- bummer.
So, instead, in nearly all undergraduate courses in
engineering, get used texts, in good condition, 5-10
years old. Such books will still be plenty good and
will save you a bundle of money.

E.g., I took sophomore calculus from the text by
Johnson and Kiokemeister. At the time, it was also
used at Harvard. It's a beautifully written, highly
polished book. Tough to write a better calculus
book.

So right away from a Google search at

http://www.amazon.com/Johnson-Kiokemeisters-Calculus-Analytic-Geometry/dp/020504218X

can see

Johnson & Kiokemeister's Calculus with Analytic
Geometry [Hardcover]

6 used from $9.25

So, can get it for $10. Don't pay a lot for a great
textbook.

Actually I got my copy 'used' from a student who had
tried the course the previous year and learned that
he should major in English or some such instead!
More generally, due to such circumstances, a lot of
used technical books are actually in quite good
condition.

You don't have to work all the exercises, but you
should work enough exercises so that you are sure
you can work all or nearly all of them. A good
textbook will have in the back answers to half or
more of the exercises; so check your work with the
answers. Occasionally an answer is wrong. If you
suspect such, then maybe e-mail the author! Or ask
a local prof to check your solution and impress him
that you beat the textbook!

Occasionally let a difficult exercise go unsolved or
ask for help; in some books, 1-2% of the exercises
are in there poorly written, out of place (need
material not yet covered in the book or not in the
book), or are to see if a student can recreate some
brilliantly clever argument mostly unrelated to the
book. Don't let yourself get hung up on 1-2% of the
exercises afraid you missed something -- give such
an exercise a good shot, then just ask for help or
drop it.

Continue this theme of self study, especially if you
want to go for a Ph.D. E.g., at one time the Web
site of the Princeton math department just flatly
stated that the graduate courses were introductions
to research by world experts; no courses were given
for preparation for the qualifying exams; and for
the qualifying exams students were expected to
prepare on their own. Indeed, in that case, why
bother to be on campus in expensive Princeton, NJ?

So, broadly, you can get a Bachelor's paying little
or no tuition.

Then for a Ph.D., or even some Master's degrees, the
big trump card is having published some research in
a good, peer-reviewed, academic journal of original
research.

For how to do the research, that would need another
post!

In the whole thing, nearly all the work was
self-study from used textbooks, and the tuition you
paid was tiny. You cut down on time and cost
commuting to campus, eating campus food, etc. You
aced nearly all your courses, and you avoided a huge
list of potential 'political' and other problems.

Learning is not a spectator sport but an individual
thing with hard work, done alone in a quiet room.
You can blow a lot of time and money going to class
when what you really need is just hard work, alone,
in a quiet room, which, indeed, the courses won't
much replace anyway.

Not everyone learns the same way. But, since you
learned the material before you took the course, the
profs never get to see how you learned; you never
fell behind in a course; you aced courses, and you
never got criticized for your learning style.

Net, lack of money is no great reason not to get a
degree, even a Ph.D., in engineering. Indeed, the
main challenge is just the learning and, then,
research; if you can do that, mostly on your own,
then money for your degree is not a biggie.