Lucky twink blues from lowbie instances FTW. By the time I hit 30 I had x3 the amount of money necessary for the mount xD

On topic: Eh I'd send the money back, however I wouldn't expect your average barrens/trade spammer to even give it any thought. I guess it's down to luck for you. Oh and you said it was Linen so it's probably gonna be a noob, 50g will set you up for life at those levels, so I'd veer more towards accepting you ain't getting your money back.