Dave I really think that was a phoney auction. Same person bidding it all the way up. Nobody in their right mind would pay that much for such a common part. Heck, I've seen complete radios with bezel and nobs sell for $25.00.
take a closer look, there were 2 bidders bidding each other up. I sold stuff on ebay about 6 or 7 years ago, and you'd be surprised what sells and what doesn't. I've also noticed that at this time of year things go for surprising money, possibly because people are trying to get their cars ready for spring, and will pay big bucks for something they really need.
1956 Pontiac Pathfinder 2dr sedan, 496 - dyno'd 545 hp, stick shift, 4.11 posi - Hot Rod