there's some info on B&S saxes here -
http://cafesaxophone.com/showthread.php?4221-B-amp-S-saxophones
If you're thinking of buying a Sonora, just check the usual things like intonation/tuning, damage and wear and tear and if the pads seal properly - the problem with these East German saxes is that the cost of a full repad and overhaul is more than the instrument's worth. It's only the professional 2000 series B&S saxes and the blue label ones that are worth any money, the cheaper student horns like Weltklang, Sonora, Musica, Berg Larsen, Trafford etc are fairly common and aren't highly regarded in the UK - although in the USA there are some dealers charging higher prices for these instruments based on the reputation of B&S's pro instruments.
The keywork is clunky and basic on these things and they're heavy and solid, with a tone to match.
Several years ago my friend brought round his expensive Keilwerth tenor. After admiring the beauty and sound of it, I jokingly got out my Trafford tenor to compare. When I blew it, it sounded similar to the Keilwerth, although that's the only similarity - the Keilwerth is a far superior instrument.
No doubt some american sax dealer will start selling Weltklangs as "poor man's Keilwerths" in the same way that Bundy's are being sold as "poor man's Bueschers"
Trafford saxes were imported from East Germany in the 1970's by Barratt's, a music shop that used to be on Oxford Road, Manchester. A lot of them were shipped over in bits and assembled in a workshop in Trafford, hence the name.
If anybody wants a Trafford tenor, let me know, I never play mine.