Just to let you know how much time spent on it already. I started something around 01.01.2014
I spent every day 2 - 3 hours from mo-do, fr around 4 -5 hours, Sa + So arround 8 - 10 hours. Count up this for one week are 57 hours.
57 hours * ~12 weeks 684 hours.
I think it does not need a fully perfect working program to start donations and also I don't think that Windows are the only people who would donate. And as you see, the work time is very high. I think a gift to tell me that I should develop further is ok.