If you want a Microchannel workstation I can recommend the 7006-42x Models.

120MHz PowerPC 604 and a very fast graphics adaptor. Ethernet and SCSI 
onboard. Nice form factor and low noise emmission.

The 7012-397 has much faster CPU and you can put in more RAM. The 
onboard SCSI is a Corvette (and you have the same connector for 
attaching external SCSI devices )

If you want a RS/6000 but not limited to Microchannel you can go for the 
7043P Models 140 or 150.

There are nice server models for low budget available. But only if you 
don't sit in the same room with those machines. They are built for the 
server room and not for the living room.

-- 
Uli