This is a really neat project OP, and I hope you can make enough money to sustain development. I really, really wish academia did a better job of sponsoring people to maintain high quality software libraries, so you didn't have to 'strike out' on your own though.
I appreciate the thought, but if this isn't useful to support itself, then obviously I was wrong, and I should find a more valuable project. But I don't think that's the case --- I think this will help a lot of people build useful products, so the commercial license should fund its development quite adequately.
Then don't consider it a donation, but as a separate pricing tier. Currently, you are charging $5000 to those who don't want AGPL, and $0 to those who are fine with AGPL. You can charge, say, $100 to those who are fine with AGPL but want to pay.
If you want to increase sale, you could include donors' names in the documentation in return to $100, for example.
