I am not sure about a surf shop specifically, but I think you might have good luck with a beach area pawn shop also. Probably easy enough the do a yellow pages search for that.
What about craigslist? A Houston CL search find sevral. They seem to start at about $200. Except I found this ad in Sealy looking for a trade:
http://houston.craigslist.org/bar/1090998490.html
Sorry, this probably isn't much help for you.