You can get the 8 meg ones only through OEMs.
I think I know why youre seeing this price incosistency: The 16mb v550 comes with a TV-out...the 8mb doesnt. They charge you through the nose for that.
I dont know where you get your prices, but you ought to shop back around once more at pricewatch. You can get a 16mb Creative Labs ot STB card w/o TV-out for less then $90. If you dont need TV-out dont insist on Diamond, many people do for no good reason. The CL is just as good, perhaps better because they make excellent drivers.
This signature space FOR SALE