Will it be possible in the future to sell some of our stuff in the inventory? I would really like to sell a few hats I accidentally bought :P

yea nice idea,
also how about opening a Market?
for example, there could be some limited-time hats or island parts.
and it would be possible to trade them in the Market :o

^^^^ I likes

We currently do not have any plans to add this into the game.

Limited edition hats, weapons & island parts however....