Camera ShowsForced onto the Endangered Species list by the Internet, your local Camera Show still offers some of the lowest prices and most interesting camera buying times. Post Camera Show schedules in your area, and your Camera Show Experiences.
I think KEH sponsored something like a used camera swap meet in D.C. a few months ago. Other than that, I've never noticed any camera conventions roll through town. Maybe the folks at Service Photo in Hampden might know.