If he asked you to get the brakes and paid you the money then he OWNS them, it's HIS fault he then decided to go elsewhere. I wouldnt of even bothered trying to sell them for him i'd have sent him the kit and told him to fuck off.

You wouldnt go to ford give em 15 grand for a new car, then when it turns up tell them you dont want it anymore and ask for you money back. Fair enough the timescale is obviously a bit longer but business doesnt work like that. He should of asked you not to buy the brakes if he didnt want them anymore.

This is probably why I dont sell things to people