Let's say (hugely optimistically) you work your butt off and complete all 8 games within a year. You just used a whole year to make $8000 that you've already spent.
Again, I like the idea, but I don't think there's a one-size-fits-all price that will be fair to either party. I hope you've explored the legal ramifications of this setup. If you can't make the games in a reasonable time frame, are you going to be on the hook for all this money?