Skin Trading?

Gambling with mystery skins is a lot of fun to do, but sometimes (All the time) you will end up with skins for champs you don't play or more then one skin for a champion. That or you get a skin a friend of yours wants but its not available in store.

Riot could easily make some good money by adding skin trading.
They could add a charge price to trade skins with other players. The RP price is up to them, somewhere between 100 to 300 RP seems reasonable.

What ideas do you guys have on skin trading?