too right it should be banned! i was bidding on a boss LS2 pedal when the seller ended the sale early - obviously wasn't getting what he thought it was worth
OR WORSE, he got an offer on it and decided to rip the high bidder and not pay the Ebay fees.
That has happened to me 3 times in the last 2 months for guitars. One of them even had the nerve to tell me "he had an offer he couldn't resist" when I emailed him and said "What happened to the auction?"