Just a quick pic of my triple GT 240 workstation:

Details:

• Foxconn ELA with 3 PCIe x16 slots running at x8.  The motherboard has an IDT 89HPES24T3G2 PCIe switch hanging off of the P45's second PCIe port.
• Three MSI GT 240 DDR5 GPUs.
• Aggregate of 3*96 CUDA cores per card is 288 cores.
• The MSI GT 240 DDR5 cards were $50 each (after rebate)!

Why three?  Because it's easier to debug my code with this arrangement.  Also, the $50 GT 240 supports CUDA Compute Capability 1.2 and has 512MB of GDDR5 memory giving ~60 GBytes/sec of bandwidth.