Comp USA has AMD Desktop Barebones Kit: FX-8120 8-Core AM3+ CPU, MSI 760GM-E51 Motherboard for $424.99 - $75 in rebates (linked below) = $350. Shipping is $11, so the grand total is $361 plus any taxes.
Available Rebates:
MSI 760GM-E51(FX) Motherboard $10 rebate
CORSAIR Memory (model CMX4GX3M1A1333C9 XMS3) $20 rebate
CORSAIR Memory (model CMX4GX3M1A1333C9 XMS3) $20 rebate
MSI 760GM-E51(FX) Kit $25 rebate
Bundle Includes
MSI 760GM-E51(FX) AMD 760 Socket AM3+ Micro ATX Motherboard
AMD FX-8120 Eight Core 3.10GHz Processor
Sony Optiarc 24x DVDRW Drive
4GB Corsair XMS3 DDR3 1333 Desktop Memory
4GB Corsair XMS3 DDR3 1333 Desktop Memory
1TB Seagate Barracuda 7200RPM Hard Drive
Thermaltake V2 ATX Mid Tower Case w/ 450W PSU