I think that you would make people happy with a price like that.
As for the X1900, there are new, ready flashed 256 MB cards going for as little as $90......
Sellers of 512 MB versions are asking $200 and up, $260 showing as a current asking price by one, long time "retailer" (it'd be different if he actually wrote the ROM.......) People actually selling cards (read "moving) are selling for $50-$60 less than the lower figure....
It's whatever the market and conscience can bear.
The higher the price, the greater the requirement for service and support, the greater the risk for trouble, bad feedback.....
I find people that feel like they got a "deal" are the happiest, and that, in turn, typically results in lower risk of trouble.