One ATI 5830, Approximately 245 Mhash/s

Power Supply    Rosewill Green Series RG530-S12 530W, 80 PLUS Certified   NewEgg    $50
Motherboard    Foxconn M61PMP-K AMD                                           NewEgg    $45
CPU                    AMD Sempron 145                                                   NewEgg    $39
Memory            2GB DDR3                                                                   NewEgg    $13
Graphics card    Radeon HD 5830                                                           NewEgg ($153)    $110
Storage            Western Digital Caviar 80GB                                           NewEgg    $17

Total    (Approx: $1.1755 /Mhash)       $285 + s/h/t

However as ASICS are about to ship out the doors and double the difficulty, GPU mining rigs are about to go the way of CPU miners and be obsolete!

But there is still hope! ASIC miners cannot mine LiteCoins (For Now) and this set up will work for LiteCoins with similar results.