I don’t think I have ever paid any real “collector’s price” on a soundtrack CD… I remember back in the 1990s some crazy auctions on (the then comparatively new) eBay, where CDs sold for hundreds or in a few cases over a thousand dollars. Those were legendary discussions in rec.music.movies. I still have a printed film music “pricing” guide from around that time. I have only ever paid for what the CD would have cost new more or less anyway. The very few CDs I absolutely wanted to have and initially missed (like Ennio Morricone’s THE ISLAND) I traded for something else later on.
I would have paid $25 for FUTUREWORLD now, as it belongs to a special type of film score (it’s among film scores I initially taped of the TV, scores that got me interested in film music to begin with), so I’d love to have it.