Bingowings said:

If you cut out the middle men whatever gets paid ends up in your collection tin without having to give over the major chunk to a corporate fat cat.

So while it might take time it's pretty likely that at the least you will make your money back.

Has there ever been any successful examples of depending on fan generosity?

The only example that's even similar that I can think of was "Dr. Horrible's Blog" and that was produced by a group that already had a huge following from real media. It also was only available for free for a short time.

Idealism aside, a business model that depends on a small percentage of rabid fans to be willing to pay more than the entertainment is worth in order to cover for the countless hordes of thieves strikes me as unlikely to work well.