Q:

Is it okay to join a self-funded PhD Program with possibility/intention of leaving in future for funded position

I have done my masters a couple of years ago and now I want to do my PhD. I have been trying to get funded positions but no success yet.  Without wasting my time, I am thinking about joining PhD program on my own funding.  I know it will be hard for me, but I can do parttime work etc.  Moreover, I am thinking to keep applying for funded positions or may be the current professor has funding later on.  
I am not sure if it would be okay to leave a phd position.  I read here that it would be unethical to leave a funded PhD and they have valid reasons that they fund you and invest you.  However, in my case, I am totally self-funded.  
So my Questions are: 

Would it be okay/ethical to leave phd given that I am self funded. 
Will I get any PhD position if I tell this to professor/admission committe? 
Should I tell them upfront about the possibility of me leaving before? 
will professors understand my justifiable reason to switch to phd to a better and funded position?  May be I need a recommendation letter from them in future and I don't really want to create any bad impression of myself. 

P.S. 
Reasons to register for self-funded phd position:

I don't want to waste my time any further; it has already been an year and a half. 
I shall get a research experience and will be in academia network that will help me to get a funded position.  

A:

The only ethical concern here, hence the only thing that would make it not ok, is if your leaving breaks commitments to others and leaves them hanging.  This might happen in some lab-intensive fields where your research dovetails with that of others.  In that case you would need to clean up the situation, but still aren't obligated to continue forever.  
Most people will understand your situation and your desire to move if you do.  I don't think that obtaining letters will be a problem as long as you fulfill your obligations.  If you are doing good work, there may even be an incentive at the first institution to find funding for you in some way.  
The only negative I can see is a question might arise about why you can't get funding.  Is there some deficit in your background.  That might make it harder to get accepted, but otherwise I don't predict any  issues.  
Actually, people leave funded positions as well.  The same basic rule applies.  Fulfill your obligations and don't leave others hanging.  Laws and contracts may modify that rule in some situations, of course.  
Joining a doctoral program isn't a one time, irreversible, life-time commitment. 