How many times has this been suggested?
If they where to allow us to make money by selling hats we bought or have it would never be for any kind of profit. The resale value would actually be quiet low on most stuff reguardless of rarity.
It doesn't matter anyways if you make a hat you can send it to the staff through email or whatever,and if they decide to use it they will give it to you for free in game and a one time payment for whatever they decide the price is going to be. So you can some what all ready sell hats you made. Other than that they will never allow players to sell hats or any items in game for gralats. There job is to get players to buy gralat packs not allow them to make gralats in game easily. No company in their right mind would allow you to resell a product for the same price that you paid for it. so selling a 5k hat for 5k isn't gonna happen. It would be more like 500 gralats for a hat you paid 5k for.
Not saying it wouldn't be cool it just wont happen because they cant make money from it.
Ppl keep asking for trading,and that would be cool as well. But I will say it again. There is bound to be drama,scamming,and other issues so its best to just not do it.