Sell back?

Hey all I want your opinion on this, I like the game but one thing I wish would add in is a option to sell your weapons. For instance if you're hunting region 6 and need just a little bit of cash to upgrade why shouldn't you be able to sell your guns from lower regions like region 1? It wouldn't really take away from paying for cash it would give people a little for options if they are unable to buy cash for the game.