Every company/product with a strong community and few employees that I've seen try this has worked massively well. http://unknownworlds.com/ is a great example. When it was still just a halflife mod, and the creator wanted to work on it full time while bootstrapping the company, he asked for donations to get a special icon in game and playtesting access. There was an incredible outpouring of support and it kept them…
Sometimes the worth of something, and the spirit of those pursuing it, is worth reward/support in and of itself.