For corsair, best bet is the CXM 550w. Usually cheaper than the 550w RMx, you could also do a Seasonic M/S12-II 520w or 620w, XFX TS 550w, Antec HCG-M 520w/620w, Evga GS/G2 550w etc. These usually run in the $50-$70 range, but sales can change that, I've seen the XFX at newegg for $25, the Antec HCG-M 620 for $30 etc.