A Weaver ZB for $15,000!! This must be some kind of a joke, or else the vendor must have been having the DT's when he was typing in the zeroes.
I'd expect to see a photo of the heel with its characteristic rounded shape, or were some made differently? I have a banjo purporting to be a Weaver but I think I was had. I don't know too much about Weaver ZB's. It could be 'A. WEAVER, MAKER, LONDON stamped on the side of the heel of mine, but it's very faint and I can't be sure. Mine is very similar to the one for sale in Texas.
When I try investigating the vendor I get a sign come up saying 'Closed Permanently' so I'm a bit suspicious to say the least.