Rosewill RSV-L4412U 4U Server Chassis Rackmount Case 12 Hot Swap - $249.99 FS @Walmart via NewEgg or Direct at NewEgg - Several other models too

Rosewill RSV-L4412U 4U Server Chassis Rackmount Case | 12 Hot Swap 3.5", 2.5" SATA I, SATA II, SATA III SAS | E-ATX Compatible | 3 Front 120mm Fans, 2 Rear 80mm Fans | USB 3.0 2.0 | Front Panel Lock. It is a budget 4U 12 bay server chassis. Seems to be lowest price I can find, maybe historic low too. Several other models available. Available for $249.99, more than $100 off MSRP.