First of all, this is computers. The more you have, the more expensive it'll get per increase. The bigger you get, the price increases exponentionally. Like of couse 1gig will not be double the price of 512, cauze then under the same logic i'd go buy 2gb ram for 4x the price of 512. But wait, 256 mb, is cheaper, so why don't i just buy 2 gigs of ram for 8x w/e 256 mb cost?
Anyways, that won't make up for 100% of the cost. I think that the qualitiy of the ram varies. So the 1 gig of ram is higher qulity than the 512 ram.
AMD Newcastle skt 754 3000+
Elitegroup 755-A2 ATX motherboard
512 DDR RAM
120 gig PATA Hard drive
128 mb AGP 8x ATI Radeon 9250
300 watt 12 volt psu
Antec SLK 1600 case