Trade Ins

I know Riot makes all their $$ off of RP sales, and I wouldn't want to cut that. League is awesome, and I don't want to hurt that. What I was wondering is if there has ever been consideration given to being able to 'sell back' champions you don't want/play? When I first started, I purchased ALL the low tier champs through most of the 1350 IP range, and very rarely use any of them any more (except Annie, Caitlyn, and Garen, duh). I mostly play AP specific champs (support/mid), and wouldn't mind an option of some sort to weed out my collection. Even if it's just a trade in for IP, that'd be great, but a reduced RP trade in would mean I'd be taking it and either buying another champion or skins for the champs I already have and use (which is why I don't think IP is as good an option).

The issue I can foresee with this is people buying champs for IP and trading it for RP over and over to build RP (just being honest, I probably would too). To stop this, I would recommend a point limit before trade (IE 3 mastery levels?) or a time related delay before you could trade a champ.

Thoughts?