I cannot help with your particular buyer, But I do trade online all the time and accept payments from pay pal for order up to and above you sale,
I take a few simple steps to check people out and make a judgment them. then cross my fingers
a, Get the real name and address... type this into Google and variations and see what it come up with, eg. (the address might be a factory and not a private house)
it might not be fair but is the area they are in consistencies i.e with spending $400 on vintage a luxury spend.
use you common sense to see if things look ok. Most people come up with reference on Google these days
b How are they going to pay, suggest a different way .. like cash see what they say. if they are running a con job on you then they are all set up and you changing their plan upsets it, explain with large sales you like cleared funds before you send goods,
c If they are asking for a very fast delivery which cost a large amount be carefully, as con always want the goods quickly so they can cover the tracks and as they are not going to pay you anything it is irrelevant to them how much delivery costs.
D See what else they have bought on Ebay is it a consistent , like all clothes , are they all expensive items?
E In my mind it is all about trying to work out a little about them, their habits, and finally how they can con you and get away with it.
It sound like a load of rubbish I written down but it's from 27 year in retail, it's sort of bluff if a con person thinks they have been found out they will run first and move onto a easier target, even if you are not 100% certain at the time ash questions?.
Honest people always understand, any question make them sound ambiguous then a con man or lady will pick up on it and the honest person will read it the other way and not be offended.
Good luck.