Thanks for the suggestions. I am not sure if a slightly slower RAM would reduce the cost all that much, I am looking at getting Team Xtreem LV 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 2400 for $69.99 and, at least, on newegg, that's one of the cheapest one.
Yeah I can definitely keep my PSU (750W)...