I was just looking at the items in my inventory and this one had no listings in the user shops. Is it worth anything?

priceless....its a nontradeable item.

You can wear it....or put it in your vault :p.

[edit] or transform into ....but thats also the same situation [/edit]

unfortunately, you can't sell it. it's an account-bound item that you can either store in your vault or place in your wardrobe. it transforms into or and back into for whichever style suits you. the transformations are not permanent and can be done at any time.