I would have bought it in a heart beat for $2k-$5k. But 50k is really out of my league. Have you considered selling licenses instead. I don't care if I am the only one who owns the code. You might get more sales as well that way.
(Any entrepreneur with the cash is, of course, welcome to purchase it and resell the licenses yourself! You'll need to be quite tech savvy to maintain it though. I'd spend my integration week however you want, including teaching you everything about how the code works.)