The price of Rockman X100's has exploded in recent months. They used to be snaggable for a hundred quid but now asking prices are around £350-500. A quick search on YouTube will reveal a slew of videos posted in the last 6 months by vloggers which will have probably been driving demand.
Why?
Def Leppard used them to record their Pyromania and Hysteria albums at the behest of producer Mutt Lange.
Interestingly Mike Shipley (RIP), the engineer on those albums, has publically slated the sound quality of the units. He emphasised how much eq-ing was needed to get them to sound right. Phil Collen didn't recommend them for use live use either and this was all years ago. But nevertheless those prices have climbed...
... as will anything else seen as quintessentially top 40 eighties rock. Hamer Steve Stevens signature models for example. Prices of Fender Stratocaster Elite, Plus and The Strat models are climbing despite well documented tuning issues on the earlier versions.