I don't think I've really paid too much for the bike/project, all the money ends up in the WORK.
I've had a lot of bikes under $100, a few that didn't cost me anything, take it away, gifts.
I tend to spend more to gussy up an otherwise working bike than it cost me.
But if you look at the ones I have you can see I think it was worth it. I didn't spend more than I had, got things in pieces, and I found stuff, improvised.
I can't complain, it wasn't super quick and easy, it was fun. I ride them. Fixing, that's like having a kid that needs a dentist. A responsibility. Still fun, when you get it back.