I bought 2 Mark IV's last year, first one, in near perfect shape from a guy on TGP for $900. The next for $999 from GC used. That is a very early one from 1991. It came in a road case and was obviously used hard. Sent it in to MIke B for a full overhaul and am still into it for under $1500. I think used prices will come back to earth once all the free money dries up and people are forced back to reality financially.
They are great amps, but I wouldn't pay the current prices. They sound good but there are better options for $2k