A couple of deals on eBay right now:
Opteron 6124 CPUs for $75 or best offer. 8 (1.8Ghz) cores and just 65Watts. Virtualize a pile of low-usage servers for dirt cheap.
Operton 6128 CPUs for $77 - 8 (2Ghz cores) and 115Watts. Two or four of these make a surprisingly powerful server.
Opteron 6124 CPUs for $75 or best offer. 8 (1.8Ghz) cores and just 65Watts. Virtualize a pile of low-usage servers for dirt cheap.
Operton 6128 CPUs for $77 - 8 (2Ghz cores) and 115Watts. Two or four of these make a surprisingly powerful server.