I go to a few auctions every year and have managed to find a few good deals, but mostly, I walk away from most things that i was interested in.
I spend a lot of time on Craigslist and the free classifieds paper. I have a good idea of what things are going for and what they are worth. I've seen used stuff sell for brand new at auctions, and junk go for what working stuff sells for.
Auction fever is a very real thing. You have will hear it over and over again, know what you will spend and then quit when it goes over that amount. Its only a good deal if it's for that amount or less. Don't second guess yourself and NEVER FALL IN LOVE WITH IT!!!!!!
I've missed out on some deals this way, but I never regret not buying something. There is always another auction, and there's always something else out there.
Just because it's a good price doesn't mean it's a good deal.
I had a problem with my dozer. The hydraulic pumps were fading on me when the engine warmed up. I had it hauled to the dealer and they told me that all three hydrualic pumps had gone out on me. This was total BS. I had already rebuilt one and the odds of all three failing at the same time told me they didn't test them or didn't have a clue. They wanted $25,000 per pump.
The service manager and several mechanics all said to put it up for sale at auction. Nobody would be able to tell the problem when it was cold, and I should be able to get a good price for it as it is. I declined and after a lot of reading, found the problem to be in an adjustment the regulated the pumps. A simple turn of a nut solved everything.
A guy I know who has equpment and has done work for me in the past bought a backhoe at auction that sounded great and went for a good price. After running it a few days, he realized it didn't have the power that it should have. He got to looking at it closer and discovered that one of the injector lines had been plugged with a BB. No fuel was getting to that cylinder, so it sounded like it ran fine, but under load, it was gutless. The engine was toast and he had to buy a brand new engine for it.
My point is that you don't know what you are getting at auction. Check it out, look for leaks or brand new paint to cover up a problem. Try all the controls, and listen to your little voice for red flags. If it's something you cant' test or try out, walk away. Too many hide problems by pretending that something simple is what's wrong when it's really something huge.
I was looking at a used Kawasaki Mule. The owner didn't want to let me drive it because the water line to the radiator had a leak in it and he said he didn't want to engine to overheat. For $5,000 he wasn't willing to replace a hose on it. This was a huge red flag for me and made me question the owners integrity. I walked away and think he was hiding something by not replacing that hose.
Go into it looking for problems and ways that an owner might hide those problems. Lots of items at auction are legit, but it's also a good way to sell somethng without having to deal with an unhappy owner who got screwed by paying for it and finding out it's total junk.
Good luck,
Eddie