Hmmm...we don't have specific rules against trades in the classifieds, but we do require that a price is provided for items listed. So, that "price" could be the item required in trade.
The determining factor would be what the typical market value of that trade item would be. One reason we require prices is so that we can determine what ad fee applies to the ad, so if it's easy to determine if the item you're looking for in trade is typically worth $0-250 or $250-1000 (the two levels of ads we offer), we'll likely be able to approve it.
Contact me via PM or email to discuss the specifics of the situation, and I'll let you know if it'll fly.
Thanks for checking in and for your interest in the classifieds!