There's a free webapp I develop and I use a feature request system where each user gets limited votes and it works great. Since I don't get paid for this though, I was thinking of turning the most time-consuming feature requests (that are in line with my vision) into mini, crowdfunded projects, where I tell users how much money it would take for me to work on them and they can pledge money towards making it happen. When a feature reaches its goal, I would start working on it.
This might not sound like a QA question so far, but I'm worried that this might have unintentional cultural side effects and cause a lashback from users. Has anyone done anything like this before? What should I be worried about and what can I do to ensure that I maintain a good relationship with users? I don't want them to feel like I'm blackmailing them or anything.