I think there are a few things at play that drive prices up, which is why you have to simply choose your maximum price. can you get deals on auction, yes, but not too often. It usually involves a typo in the ad, etc.
1 - Shill bidding does occur and the OP's example is likely that. During an auction, I always check who I'm bidding against, what they've bid on in the past, etc. Again, i have a maximum, but if i'm better off chasing another auction, I can bail early.
2 - not everyone has a gun store nearby - this is what could be driving new gun prices on auctions. I've never seen a good price on a new gun, unless it was listed by a local shop that also runs auctions. Tanners comes to mind. They are 30 minutes from me and buy dozens of one model, then sell an very reasonable prices. The shop works on volume, not margin, and everyone wins.
3 - Market Manipulators - gotta believe that's going on as well. Sure, they might get "stuck" with one, but when they factor in the many others they bought below the normal market value and the fact that an auction loser might be motivated to bid up the next one, I'd think the manipulator can come out on top. Not sure how I feel about this method. If a manipulator was simply buying all of the models, to corner the market, I would have no issue with it, but trying to manipulate it seems...off to me, even though both have the same result.
4 - the 15 minute rule drives me nuts and is also why you simply need a maximum to bid.
5 - desperation - guilty on this one once or twice. The ladies of the house are left-eye-dominant, which means I'm chasing down LH rimfire rifles and Remington 1100s. I prefer the gas operated, to help with recoil and the newer gas operated shotguns aren't inexpensive, so I'd rather buy the older quality, for a similar price. And I just did on GB $$$. Supposedly a new old stock 1100, so we'll see how I did!
Think about S&W 3rd generation pistols in this same regard. If you want an all/mostly steel pistol, or heaven forbid, single stack pistol, are there really any newer models that fit the bill??? Although you can't buy the history or prestige, newer revolvers are robust and a decent value for the dollar. Pistols, I'm not so sure about.