^basically,if you wanted to purely sell,then you should have gotten a table in the dealer room.
but if you have say figure a that costs 20 bucks,and you trade a guy for a figure that costs 10 bucks,then you should be good to collect the 10 bucks extra cash.
if you couldn't register for the dealer room for a table,and you do plan on straight "selling" and not trading,then your hotel room or even car trunk would suffice,but i do know it's pretty frowned upon to just "sell" at the parts trading party,the name "parts trading party" says it all.
hope that helps