Surely by now eBay is wise to the 'buy to grade' return scam? Actually, on second thought...
In other eBay news, there's one buyer in Australia who consistently sends me messages with what he tells me is the price he'll pay, but never an actual offer. Recently he accepted an offer I sent out, then messaged me to tell me I better give him a "great price" on other cards he wanted. And by great price, he meant 15% of listing price.
So, naturally I wait for him to submit actual offers on the ones he wanted - he never does. These days, I'm super trigger-happy on cancelling unpaid orders for 'buyer has not paid' because f*** these time-wasters - they can take the strike, I don't care. So I did, and then days later he sends me another message asking why I never sent him offers on the other cards he wanted, and also why I cancelled the unpaid item.
Turns out he has too many unpaid items to be able to make offers/bids on my stuff, so that's why he was waiting for me to cater to his hopelessness.
f*** these people right in the ear.