I seem to buy something at every gun show I go to (except the first that was a couple years before I ever bought a gun- I just went, had sticker shock since for some reason I thought I'd be able to get something in a better caliber than a .22lr Ruger MkII new for around $200 and just drooled for a while).
I usually just buy ammo or cleaning supplies (partial list of purchases):
-misc. boxes of ammo
-a case of Fiocci 9mm (love the stuff)
-half a case of Wolf 7.62x39 (fine in Warsaw Pact rifles, I wouldn't take Wolf, even a case, in a pistol caliber if it was free)
-speedloaders for a K-frame
-lots of cleaning supplies
At my last gun show (last summer) I bought a Colt Police Positive Special in .38spl for $175. The finish is somewhat worn, but as is typical for many .38spl service revolvers, everything else is perfect. I think it spent a lot of time in a holster but it has probably been shot more by me in the 6 months that I've owned it than it did in its entire life before me (and I think they stopped making them in 1973).
Plans for future gunshows (over the next year or two, starting in about 2 months):
-tons of ammo and accessories (of course)
-used AR and/or AK
-used Mini-14
-try to find a good deal on a shotgun or two
-try to find a good deal on a used bolt rifle (flexible on precise make and caliber but in the Rem 700, Winchester 70, Ruger and Savage quality range)
-new or used Cimmaron or Vaquero (pair preferably) in .45lc (.357mag or .38spl are the alternates)
-as always, good deals on used revolvers