I'd like to re-suggest this as well. It was buried.
@DarkstaR, @Syntax, @jo3bingham, @Messed Around, @Infernal Bolt, @Luls
And while I'm at it, might as well suggest what I've been thinking of for a while: A graveyard of sorts for the trading area to separate old / inactive threads from the active ones. Maybe the rule state, "If your thread has been inactive for more than 30 days, it will be moved to the graveyard." The graveyard can act as an archive for older threads (closed, unable to post).
Why do this? Organization and efficiency. It will help with searching within the trading area by eliminating the invalid (old) threads.