Wow, I love soundtracks, especially from the 80's and older when they actually put some effort into them. I have a crap-load of pre-recorded cassettes but I don't remember having more than a handful of soundtracks, they tend to be really rare on cassette. I have a ton of soundtracks on albums and CDs but the cassettes are limited to something like Top Gun and one or two others. My buddy worked with Hans Zimmer, he said they don't soundtracks with various artists anymore because they are afraid of annoying cinema goers if the selection is wrong. I lived during that era when soundtracks either had great bands doing great songs or great mood scores that I can still identify today after a few notes. I also just watched a video on YouTube and was very deflated when they played older music that "inspired" (or ripped off) the theme from Star Wars and Jaws.
I was lucky to get all these OSC from a seller in the US a few years ago at a quite good price (around 3$ each) but they are scarce indeed. Yesterday it was the Intl discshow here at Barcelona and I got another in cassette and a few ones in vinyl, some of modern movies in 180g. I love soundtracks, specially from great composers like Hans Zimmer or John Williams.