MBG Found a better price

Just got done over by a buyer who opened a return request for 'found a better price'.

It was opened before they'd even received my item and they did not need to provide any proof that they had found a cheaper priced item (even Officeworks etc 'beat any price' promo require a receipt).

I know for a fact that there aren't any cheaper replacements available in Australiia (I import the item that I sold).

Of course I had to refund the buyer for the original postage & the brand new tough bag

So basically I'm out of pocket and I've spent time packing, responding, etc to the request. I'm losing about $15.00 an hour on this transaction and my 15YO daughter is now earning $25.00 and hour more than me! 

You'd think at least in this scenario the buyer would have to incur any costs to the seller.

I was hitherto under the illusion that I sell on eBay to make a small profit on the things that I sell...