Classified (Gumtree type) Scam

I guess it either ends up as a "goods not received" and refund scam; or more likely you'll be asked for some sort of fee to complete the sale (perhaps to the shipping agent): maybe the latter followed by the former?

I don't think asking for PP deets is part of the scam (as FFM says, that's needed to make a payment), rather it's part of the smokescreen.

That was my best guess as well. I don't bother with any overseas sales, just because it would seem much more of a hassle to get anything resolved if I was subject to such a scam.