I absolutely agree.....if you want a rusty Raven .25 that is missing pieces, Sierra is the place to go. But, if you know what to look for, there are usually one or two really nice pieces hidden among the pot metal junk guns.
Standard auction rules apply: know what you're looking at, research everything, and don't ever get excited. Place a limit on yourself and stop when you get there. My personal rule is that firearms have to be 50% or less of the "rack price" at Cabelas. Accessories have to be XX dollars under retail, with the XX determined based on how common it is to find whatever that thing may be. Fees and tax have to be included in all price calculations. Standard price on Marlin .30-30's in the used rack at Cabelas is $400-$450. There are several on the auction now right around $200. IF they're in decent shape those would be a good pickup. Marlin model 60's typically go for $50-$60 dollars. 10-22's usually go for about $100 below new retail.
I approach it as entertainment with the occasional deal. It's also a good way to gauge the market and useful as a reference in face to face deals. An example would be the AR magazines in the pre-election auction that went for stupid high prices well over retail.