The card was actually an eBay auction item and it had had a very low bid price up until about 20 minutes before the end of the auction (perhaps because the seller has little eBay history), so I thought I might do a local pickup on it, but of course eBidiots came in and bid the price up far beyond its value.
It also turns out that upon further investigation (before I decided not to bid on it) that the card is really a 7900 GS. It's actually an older 7900 GT clocked at 7900 GS speeds. Perhaps it could be overclocked to newer 7900 GT speeds and beyond, but who wants to chance that it couldn't. The card ended up selling for $86 + $12 shipping. I would have been willing to pay $40 for it and was hoping that the eBidiots would be scared away by the lack of the seller's track record, but oh well.
I've seen a total of zero video card auctions that ended at prices that I thought were good values, so I guess I'll be waiting until a great retail value comes along before I upgrade.