I would something (PPC,CF,x86, I don't mind) that is fast on doing 68k, fits into
an A1200 (or maybe even an A600), features a reasonable current GFX-chip
(lets say something like the stuff used on VIA's ITX-boards, nothing fancy&hot),
and still is a real Amiga. Would be prepared to pay 300-400 Euro for that, depending
on features.
PCI-Slots for my A2000 would be nice, but those would probraly only make
sense in combination with an accellarator.