At the time some of the JAMMs stuff was worth a lot - probably more than it is now! Specifically 1987 and the first press of AYNIL were fetching crazy prices.
KLF8R was intensely difficult to get hold of (I never managed it at the time) and WTILS was in the shops a very short period of time. Both quickly rose in price. As far as what we now consider mega-rare ... they weren't really known about at the time. I would imagine that most of those small volume pressings were only made for their own satisfaction (without any thought to value) and hardly made it outside of a small group of people.
Cheers,
Kenny