I must admit that, since moving back to Austin just over a month ago, I've been very lucky on that score. Not too many contemporary sf/fantasy books, but quite a few classics in the field, as well as a lot of really neat older books. Most of these were going for ridiculously low prices: a 6-volume set of the works of Washington Irving published in the 1880s; a 9-volume set of Bulwer from the same period ($5 each); and an 1824 set of the Newgate Calendar; not to mention some oddities such as Incidents of Travel in Egypt, Arabia Petraea, and the Holy Land by "An American" from 1841 (this last was a 2-volume set they were selling for $1!!!), and a host of horror anthologies. The prize, though, was getting a 1795 edition of Johnson's Idler for a price I could afford; now that really made my day (week, month, year...). This was the best book haul I've had in a long, long while.