As an exercise, try discounting your heating costs for the next year to see how uncertainty can creep into the analysis. By the way, I'm not sure that I understand the Chevy Nova reference. The first is discounted cash flows, which was the subject of the article. The second is something called option pricing. An option is a contract which permits someone to buy something at a given predetermined price at a later date, regardless of what the price is at that point.
Options also have an expiration date.
In equity investing, it is only used in situations where a company is overleveraged with debt and in real danger of bankruptcy. But since most Internet companies don't have huge debt loads, we have yet to encounter anyone using this approach to value Internet companies. You might notice that there were no dollars in that equation. Anyway, this is by far the most common valuation method for Internet companies. As for where you can learn more, I recommend a book called Investment Valuation by Aswath Damodaran.