What is your reasoning for the $450 price? You can buy these on ebay for $300 and download Anorak bios mod for free.
The reasoning is these are tested and modded and working stable. Not everyone knows how to mod a card, nor has the time to learn. Also, these cards retail for $359+tax+shipping, in the end you are paying about $450 a card.
They might retail for 350 but you aren't selling new in box GPU's and who knows how long you've been mining on them.