Facebook is the essence of evil, no matter which way you want to consider it. I used to use it until a couple years ago, but exclusively to have a poke at whatever celebrity or politician idiot was the focus of media's attention that day or week, and also to follow a few artists I liked. They eventually booted me out, because I wouldn't follow their 'community rules'. Best thing that happened to me for the past decade.
Anyways, I wouldn't dream of buying or selling anything on FB. I did buy on e-bay from various people from the UK and the US, never had any problems. I bought my MF A5 CD player from a gentleman up North like that and also an AVI integrated amp, I forget where from, but definitely somewhere within the UK. They didn't even want to sell abroad, before I messaged them and politely asked if they'd bend the rules for me. I'm bringing it up because I'm Romanian and your post, which surely was not meant to, I hasten to say, sort of rubbed me the wrong way.
There's crooks everywhere, I don't think the country of provenance is relevant, is what I mean. I would buy from the Wam and send the money up front, but not from someone with a 5 post count. And I wouldn't dream of asking for gear to be sent to me before payment, that's for sure. I also don't believe in people dragging their feet until they pay. If you commit to buying something and you don't have the money ready, you're apt to be playing games, to put it very politely. On the other hand, you can easily get shafted, whichever way the transaction is going, so it's a bit of a toss up. As unreliable as ebay is, at least you do get some indication from the user's feedback, they have that going for them.