I might be biased since I had a 0 FB bidder win an item of mine early this morning and they still havent paid... And this is my second time listing this item as the last winner was a NPB as well...
I don't have high hopes that this person is going to pay, I wish I'd cancelled their bid.
That and there is always the possibility that it is a scammer.
I wouldn't sell something that costs $500 to a n00b, personally.
So sorry this is the second time you have sold a bag and it is potentially another NPB. I had 2 this month and 3 last month, but one finally paid the day I filed. They didn't leave feedback so for awhile I was waiting for some petty claim of SNAD or something else.
Good luck selling your bag!!!