I think the Peavey stuff had its demand spike from several different sources. Nostalgia/midlife crisis, copycatting famous bands/recordings that were discovered to have used Peavey (mostly solid state) amps, and the JCM800 price inflation.
Over the years I had always sort of kept tabs on a lot of the under-the-radar JCM800-based amps. Sovtek, Red Bear, Laney AOR, the Jackson JG2/JG3, etc. and watched them transition from $300 amps to $800+ as they were "discovered by the masses."
When I was finalizing my JCM2000s for my collection I did enough research and trial & error until I settled on my comfort zone for which years. The DSL50 and TSL60 definitely have the fewest issues out of the all of the models.