i know pinheads who put hundreds of hours into a single pinball machine, but i doubt that many of them (ok a few charge top dollar for their output) expect the cost of even the parts alone to be ever recuperated.
I'll never sell my DESW, it's been the biggest project I've ever taken on (piece of cake for most of you, I realise ) so it's not just the financial investment (and I've probably gone slightly overboard there so don't want ot add it up!) but also the time, effort and love!