Every time I go to an Auction, I end up paying more than the personal limits I had set for myself during the preview. We have all been there and have gotten caught up in the moment. That's what makes auctions fun.
When you are selling out of your collection "it is difficult to get a buyer "caught up in the moment" it is difficult to create that excitement and urgency to pull the trigger at home. People react differently when faced by those pressures at an auction. I would imagine that Ego's also play a role. Some people have enough money where they refuse to be outbid by a local competitor/fellow collector in a public setting. Most people are building collections on a budget while raising families and working 8-5 blue collar jobs. For others it's all about showmanship and an unlimited budget. These are the people that don't have the time or the desire to be looking through local ad's and making small purchases. They would rather drop a stack of cash at an Auction House and impress everyone, they don't care about what they pay for an item.
I have dealt privately with these "Auction House high rollers" one on one and trust me they are totally different when you are trying to sell to them one on one. They don't throw out their money as freely. In my opinion Ego's are a big part of these prices.
I am also in agreement that swap meets = deals, Specialized Auctions = higher prices. An example of this would be Barrett Jackson....privately you couldn't get the money that some of those cars get.
Dave's Garage & Memorabilia, Inc.