I also go to a lot of auctions, average a grand a week on tools. Most of the ones I go to will have the tools earlier in the sale after the box lots. It seems the men are the first to leave out here. IF they left them to the end, they would go cheap also. Tools are about the biggest draw at the auctions I attend, of course I don't do fine art, jewelry or fine furniture sales:D
I have one auction I go to every other Saturday and the tools are the first thing to sell. Note, it is located in a very white collar area and the tool selection is sparse, but often what is there is like new and often goes cheap. Bought a walk behind leaf blower for $15 because it wouldn't start. Looked all but new. Took it home, put fresh gas in it and it fired right up and ran perfectly. Sold it for $150. Bought the Mrs. a Rockwell contractor grade 10 inch table saw with a real 1.5 hp motor for $25. While table saws usually don't bring any money, this was an expensive saw and she was thrilled.
Knowing the auctioneers and there patterns help. If I don't know the auctioneer, I will call to see when the tools go off and adjust my schedule accordingly. Normally for a big sale, I like to show up an hour early to preview the tools and get a good parking spot.