I think what you did is the best way to build features for paid apps - by giving a discount or other advantage by pre-paying. For open source projects, it make

I think what you did is the best way to build features for paid apps - by giving a discount or other advantage by pre-paying. For open source projects, it makes sence for a donation to gauge interest, but I think I would still like a "contribution" or other way to recognize people that paid for features.