I bought only two books at Readercon this year, and was recommended another which I plan to buy promptly.
I bought, first, Andy Duncan's new collection, The Pottawatomie Giant and other stories, which includes my all-time favorite of his stories, "Unique Chicken Goes in Reverse," which might be my favorite partly because I first heard it live at a World Fantasy, and now I always hear Andy's voice when I read it to myself. But also because it is The Great Story of Our Time. Or ought to be. I resisted for a little while, since it was a pricy UK edition, but gave up ten minutes before the bookstore closed on Friday, and from then on carried it around and caressed it. No one else was allowed to caress it. They could only watch me caress it. Some people found this a bit odd. I don't know why. Then I hunted up Andy, running him to ground in the bar, and got it signed.
The next day, I visited the crackiest dealer in the crack den (my name for the Readercon book store), Wesleyan Press. They give conference discounts at Readercon, so I bought a book I've been coveting since it came out in hideously expensive (to me) hardcover: The Seven Beauties of Science Fiction by Istvan Csicsery-Ronay Jr. - now in paperback! I think it's going to be my next Insomnia Book - as in, it has long, complex sentences and is best absorbed in small pieces.
I also successfully pimped one of Jim Hines' goblin books (which I have not read) to a twelve year old, who'd almost finished it by the end of the con. He really likes humorous fantasy, so it was right up his alley.