uuuh....are they overseas? that is the only reason i can think they would have cost them that much. you paid about retail price for them. you can get replacement cases on the denise website i believe. i would be more inclined to go that route than to send them back. if they are telling you they paid 3xs the retail cost on them i wouldn't trust them to give you your money back.
check over their auction carefully and leave neutral feedback if there really is no mention of wear and tear.