well yeah, but i meant for like a retail machine.
oddly the build you put there is basically my current desktop. i got that $15 ECS, a $40 g530, an old case / psu i had laying around, and i bought a 80gb intel 320 for $70 somewhere (not super cheap, but well afraid of sandforce right now due to previous experiences). got a $30 GT 430 on amazon too with the $14 dvd rw from newegg last week to round it out. and $10 for 4gb of ddr3 on ebay
but yeah, for normal mom and pop at costco $500 would be fair anyway considering windows licenses, and they dont know how to build a computer and support etc. the A8-5500 by the way was $750 with a similar config but it came with a monitor