But I am in the market for a pair if anyone hears anything. I just passed on a pair of 515Bs that went on ebay for $1125. They looked clean. I was in for $800.
IMO, the seller was quite generous in his description. If those are the best he's seen, he hasn't seen very many 515B auctions. I think they brought fair money. If his pics showed them as clean and nice as they were described, i could see them bringing a few hundred more.

Something interesting from the same seller:

Full Range NATIONAL Speaker 3- AXIAL EAS-25PX13 ONE PAIR EX CONDITION NICE SOUND | eBay
Those are very interesting................... Panasonic!

Looks like they were competing directly with Fukuin(Pioneer) PAX series.