I searched the thought of selling items - like knife kits or rockets, that for now have plenty of.
I see a thread - where it looks like it was possible -http://ggnbb.glu.com/showthread.php?99912-Inventory-Tip&p=163490&viewfull=1#post163490
But it must not be the case in this version.
For example selling or Trading knife kits or rockets for Gold at reduced cost.
I have to admit, trying out the knife is pretty impressive.