Here is a suggestion for finding collectors at trade sessions who collect what you do. Put up a small flag on your table that lists the kinds of chips you have to trade (or are looking to trade for). You don't have to buy a fancy one as in the picture below. Make your own out of a portable radio with a telescoping antenna and tape a piece of cardboard to it to make your sign. Collapse the antenna and put everying back in your briefcase after the session is over.

Or you could actually make one pretty much like the commercial item by screwing a piece of broomstick to a flat piece of metal and double-stick taping it to the table. Cut a slot to fit a piece of light foam-board in the broomstick and fit your collecting flag in the slot. You may have to glue it in place, but that would make it harder to disassemble until the next trade session.

Other ideas?