Funny...I feel the opposite is true. If you order a $400 video card off Ebay, you're begging to get f*d IMO. Sure, its a great bargain after someone else has overclocked it, flashed it with the wrong BIOS, and otherwise molested it. I feel the same about CPUS or any other component worth more than $100; I'll take mine non-violated and brand-spankin'-new in a shiny retail box, thank you very much.
I've had to RMA 2 $300-400 video cards in the past, an Elsa GF2 Ultra and an eVGA 6800 GT. Thank God I bought both from reputable retailers, because:
-GF2: They were out of stock, so they sent me a GF3, which had just hit the market, for the same price!
-GT: NewEgg allowed me to bypass the usual RMA process by purchasing another card right then (which was shipped that day), and when they got the old card back they credited it back to my account. So instead of the usual 2-3 week wait, I had the new card the NEXT DAY for no extra $.
So good luck on Ebay. I guess the good part is that when you realize the card you bought is already ruined, you can use Ebay to scrape it off on some other poor schmuck looking to save $5.