Amiga hardware isn't cheap. Especially PPC hardware as it's in quite big demand. A not too earthshattering BPPC goes for ~400EUR on EBay (someone with better guestimates feel free to adjust this :-).
But you'd also need an A1200, a tower, keyboard interface, some kind of networking hardware (at least if you have broadband). I'd say ~200EUR for that lot. I think if you're really serious about running OS4 and have to start from scratch with Amiga h/w you'd be better of buying an A1. But then again, I'd wait until OS4 is actually buyable :-)
Oh and should you get a BlizzPPC: GET ONE WITH ONBOARD SCSI. Don't bother with the non-scsi species, the slow-as-frozen-crap onboard IDE of an A1200 ain't worth the money you'll save.
