While I'm on the idea bandwagon (and Lord knows I am full of it, er I mean ideas):
Have you considered posting this (the Fundraiser) as an Indiegogo campaign? The Perks could then be various # of hours (max) for a custom coded app?
It would probably be a good idea to lower expectations by calling it "prototyping".
Tons of people should be willing to pay $99 for 10 hours, $199 for 20 hours, $299 for 30 hours, & $399 for 40 hours. Imagine, they get a custom job for $9.99 per hour. It wouldn't take many to smash that thermometer. And perhaps fill your Dance Card for the rest of the year.
Followup offer to those who are close to completion within their time. They can choose to accept a working prototype with some functions working and others merely displayed as dummy buttons, or you can offer them an upgrade to finish for a fixed fee (or at your option) even a small royalty.
This idea is scalable with various coders contributing code snippets in their areas of expertise.
This could ultimately be made into a generic app where people chose which modules they want. But that would be outside of the Indiegogo campaign and likely far in the future.
Let me know if you have any interest. I have done an Indiegogo campaign, so can help with the setup mechanics.