Are auctions a "fun" atmosphere? Depends on who you bring with you I guess. The main providers of the games are usually old guys with a big truck, so they are not impressed with the history, only the prices.
If you want to see a bunch of games, usually more games than you will ever see in one place, it's great. The arcade auction usually has different types of people; Home buyers, game distributors, pinball fanatics, and ebay scouts.
Pinball guys kill me. They pay up to $4K for a old pinball I wouldn't pay $5 for, but I don't know jack about pinball machines.
If you want to get a collection of machines, auctions are the only place to go. Ebay is for people that have game they are trying to fix. Auctions are for people with big garages and strong backs.
I used to buy broken down games for $10-$50 and fix them or convert them. Take them back and sell them for $300 - $1000. It's a hobby for me, and I have the "junk gene" so I love all kinds of auctions. I would buy some games and strip them, like Golden tee and Gauntlet, etc. I did buy some old games like pacman and ms pac and restore them. I have a #@@!#$ Joust I'm working on now. I picked it up for $100 and I have had it working twice, but it keeps shorting those #@!@!@# ram switches.
I restored a Wizard of Wor I picked up for $50 and sold it for $400. That funds me. I bought some of those midway games with good monitors just for parts. I seldom buy parts off ebay unless I can't salvage them. (Like T molding, etc).
Most of what I learned came from Randy Fromm's arcade school and this forum.