Passing along a local find from Craigslist. Here's an early 70's B-15S -- last of the tube Portaflexes. No affiliation with the amp or the seller, though I did meet him today and check out the amp. The amp is real and the seller seems like a good guy. The amp is in pretty nice shape for its age. Grill and speaker replaced. New GT 7027 power tubes. Preamp tubes (12ax7) probably need replacing -- at least one is microphonic. And if I bought it I'd clean up the inside of the head, do the caps, etc. Sounds pretty darn good as is.
As I said, I have no affiliation with the amp or seller, but would be happy to help him and an interested TBer get together.
AMPEG B15S 70's