Collectors who bring a ton (literally) of plates to the convention usually don't want to have to bring it all back home with them.  In order to liquidate a lot of stock, one strategy is to  hold a half-price sale towards the end of the convention.  This is often announced over the loudspeaker, and it is not difficult to find the table if you are confused.  Just follow the collectors.  Of course you may very well be vying for elbow room as this picture shows!  A feeding frenzy likened to sharks on a tuna!