At the moment, all I can see is shops for people to buy stuff, but what if you have an unwanted item that you wanted to sell...is there anywhere or anyway that you could do this, or are you stuck with that item permanently? Plus, if you can sell it, does the amount you sell it for depend on the person selling the item? The person buying the item? Or the Mods and Admins?

No, as explained in the areas themselves. There are places for you to sell the items. Check it out. There you can sell whatever you want and also name the price. But you have to wait to see if a real member buys from you.

Oh right...coz I've been looking about and can't find places like that...perhaps I'm just not looking hard enough, :P

You can make a post of what you want to sell, as long as it is in the right location