PSU requirement for sapphire toxxic 5850

Im giving the 5850 im currently using to a friend as im looking to get a new gen card within the next few months and at the momment he has a athlon II 240 and would be getting a phenom ii 965,his other specs are 4gb ddr2, and a 210gt. The pc he has was like $50 lol so knowing that the 5850 on amds website recommended at least a 500watt power supply, with the current setup with the dual core and when he gets the x4 would 500 be the minimum? or is that just amd being safe on their recommendations and requirements? He was looking to go kind of cheap on a psu and was looking at the corsair cx series, xfx core pro550, seasonic 520, and silverstone 450watt power supplies around $60-80, 80 being around max