After WWII the old German instrument makers were nationalised, becoming Amati in CZ and VEB (amongst other names) in E Germany. The East German VEB became B&S after privatisation following German re-unification. There's another thread somewhere else with a lot more info. I'll try and find it. But B&S is not Keilwerth, their factory disappeared into Amati.
The horns are well thought of here, but not so much outside Germany. Thomsax has played a few, don't want to put words into his mouth, but he doesn't seem to think a lot of them. Fifteen hundred seems much too expensive to me, although the later Medusa horns are probably worth this sort of price.
£ 1500.00 for a B&S bluelabel. Too much! I offered Kevgermany a nice "silver" B&S tenor to high F# that they wanted c £ 150.00 for. Ok, the sax needed new pads .... but otherwise it was in good condition. They are ok, but B&S were a lowprice sax when they were new.
You can get a nice Selmer MK VII (delaquered) for 17000.00 s e k (c £ 1700.00) and that's a much better sax.
They are to be found under many aliases since they were pretty much the equivalent of the nowadays Chinese or Taiwanese saxophones in the '70 and '80 market. B&S are also known as Weltklang, their best model being the " Solist" model) but lots of people favour the Blue Shield (or label) as it was supposed to be their best production. I have played a number of them and , in fact, the later " West-German" B&S were still based on these horns but the better series (Guardala, Medusa, 2001, Codera) had much improved keywork on a bodytube that stayed the same (but in general had a better execution and more attention for details), the B&S blue shield were essentially the same as the B&S series 1000.