Just for a reality check, if you'd put this through a real auction house, what do you think the outcome would have been?
You would have been obliged to sell it, as it's a legally binding contract.......as is Ebay.
The reality is, when you listed it, you were happy with the contract terms (by implication), however, you weren't at the end of the sale.
You broke the contract because it didn't suit you anymore.
Not a cheat, but morally bankrupt.