It would be much better I think to write the stuff, then either try and sell it yourself, or via the shareware method. No-one these days is going to earn a living or get rich from writing Amiga stuff... 
Well you answer your own point, there's not enough money to be made by trying to commercialise it, and people aren't writing the software because there's little interest in doing it even though many feel that it's software we need... so how do you attract people into writing that dull software that won't make them any money from sales?
One way that works is setting up a bounty, then the few people that are most interested put up the bulk of the money in advance, and many others contribute smaller donations.
The difference is that is someone just wrote the software up front and then tried to monetise it those major sponsors would only be paying the pittance that everyone else does and so it never makes economic sense for the developer.
