I'm am just curious what you think a fully working Future Spa with a nice BG and cabinet is worth if this playfield were to be installed in the game? There has been a VERY nice complete and fully working Future Spa re-listed on Evansville,IN Craigslist at $650 for like 6 months and it hasn't sold and I doubt that it will... I wouldn't value that game at $650 because it's been up for sale for 6 months.
Similarly, I wouldn't value a mostly populated Bally Future Spa playfield at $400 either. If you want to sell it, you are probably looking at $200 or less. Don't get me wrong, it's got some decent parts on it. But once you consider shipping the thing, finding a home for that playfield will be difficult.
I remember smashing up a Future Spa with no boards or displays (not that many years ago) because no one wanted it for free.