I fail to see the benefits from this. It´s not like Altitude0 is TeamFortress2 where you can sell/buy items on steam marketplace for real money. I don´t think this will be of any use for me (or anyone else who´s not so bored out of their mind they´d have to look at their inventory items for a game they could aswell play).
edit: I see... Rare items are in fact marketable, Altitude0 really is TeamFortress2 now!
edit2: Put my Night Owl Sticker up for sale (for testing purposes) - if anyone wants to test this further: 10 bucks and it´s yours hahahaha 