Well, from the title, why can we not sell champions back? We should be able to (for a reduced cost of the original) if we don't like the champion. And if Riot wishes to only accept resales on IP purchased Champions that would be acceptable, but I believe if this were implemented, it would be a big use to people. Also, if there was a limit on sell back that would also be fine.
Sometimes some people buy 6300 champions (like me) and don't like them or just cant get into the game play style of the character. So I think this system would be very beneficial if well thought out and balanced to allow it to not be abused.
What are your thought's on this? Keep this thread alive, if we get enough support behind this idea, maybe Riot will do something, if not, submitting a ticket with this thread included might get their attention.