What were your experiences? Where do most of the cars come from? Does turnout vary wildly from auction to auction (so if you find the right one, very few people will be bidding)? Are there reputable and nonreputable auction houses to go through?
We bought an 84 dodge caravan at a town auction [from their towed vehicle/impound lot auction] back in 96. I believe we paid $800 for it. It was in excellent condition, only thing we did was run it down to the submarine base and get them to run a drug doggie through it to make sure there weren’t any ‘leftovers’ in it. Lasted another 6 years until some stupid lady tried to merge into mrAru and pushed him into a guard rail.
The auction was advertised in the local freebie [Turnpike Buyer] and was during the day on a wednesday at the town garage. They were selling off all sorts of stuff, old office furniture, stuff the town had replaced over the past year or two, stuff that was seized or abandoned and never reclaimed, confiscated vehicles and town vehicles that were being replaced. There were a few buyers for an automotive auction house in Hartford. I guess used minivans are not a desirable resale vehicle 
We also bought a spiffy [though marked up] library table - one of the churchy looking trestle tables with the rubbery insert in the top. We eventually will dig it out and replace it with a nice mosaic eventually. No space for me to really do the work here, as I can’t hook up the kiln to make the tesserae at the farm.
I would prefer a physical auction to an ebay one, I like poking around and seeing the vehicle live as it were =)
Many, many years ago I bought a $300 Volvo through a police auction. But there was so much red tape getting it registered that it cost me an additional $700 at the DMV. HUGE head-ache because apparently the title was not clear but back then (almost pre-internet), these things couldn’t be checked.
Now there are services to get a car history and I would recommend it.
Quite frequently actually, I would go to my dad to a small town auto auction. He bought cars to fix them up and re sell them all the time. Results varied, haha.