I'm going to go against the grain, and say I would be very weary about selling a high ticket item to a new buyer. In my experience, paypal usually sides with the buyer. All the buyer has to do is say they didnt receive it, or got a empty box, or make other excuses. Then do a paypal chargeback, and that's that.
The posters have made solid advice, but I would personally not feel comfortable. I've personally cancelled 0 feedback purchases, on high ticket items. Even if taking the hit as a seller, I want to err on the side of caution.
I agree. I would also be weary with a brand new account, and zero feedback. (You would be weary if it was a newbie on here)
The consequences of selling to this guy and it going tits up are you potentially losing the coin.
The consequences of not selling and waiting for the next buyer are that you may get slightly lower, but it would most likely be the safer option
I dont think its a risk worth taking. If this guy has joined ebay after you posted the auction, then my alarm bells would really ring. This coin is not widely known about, and also possibly still available from CI. So they have either seen this coin linked on here (and why not do it as an escrowed bitcoin payment then), or they already had an ebay ID that had a search alert set (and then have created a different account to buy this with). Either way it doesnt look right.
Alternatives .... perhaps a Paypal friends and Family payment .... not linked to the auction. Unsure if that would work ? Unsure if that cant have a chargeback made against it or not. Or good old escrowed bitcoins