@The Amazing Virginian
Answering here to avoid clutter in the Buy, Sell, Trade thread. (***whoops. Guess it was in the ANAQ thread)
As I understand the rules, as long as it involves a CPK, it's fair game.
You can offer your My Little Pony collection as trade fodder for... say, a DEK1 (and folks have listed other knifemakers work in their collection, as potential trade to acquire a CPK).
You could offer up an MC as trade fodder for a Conan The Barbarian sword. (IIRC, someone's offered up a CPK as potential trade for ammo, sometime last year)
But listing non-CPK items for sale, is what's not OK (i.e. spammers trying to sell their crap, so they post a 'For Sell' ad everywhere).