Right now a Evga GS 650Watt runs about $80 and a FSP Hydro G 650watt will run about $75. The EVGA G2 and P2 series are running about $99 for a 650watt. All modular and black.
Go with Seasonic S12 II 620W 80+ bronze PSU. Great PSU for the value
(It's not modular)
Othe recommendation is for you to check out the new Nox Hummer 80+ certified fully modular.