Since I took these lovely photos (!) I thought I'd take the opportunity to say why I thought the Luxors might be B&S. It's speculative but here goes.... Soviet Bloc command economics favoured large, specialised industrial units. Thus all the Czech horn makers got subsumed into Amati and all the East German ones into VEB Blechblas-und-Signalinstrumente-Fabrik (B&S). Note that these derive from established, well-documented, pre-communist musical-instrument-making traditions. Was there anything similar in Romania? Surely the Czech and East German production facilities are likely to have supplied other Eastern Bloc states.
Now, the horns are engraved "Arta Guban Romania" but the cases are marked "Arta Guban Timisoara". Timisoara is a city in Romania, and the Guban company was founded there in the 1930s. From what I can gather it essentially produced chemicals, plastics and plastic products and possibly electrical items. I cannot think how or why it would have made saxophones. However, it did make "luxury" shoes, handbags, cases etc. from plastic. The Luxor horns come in very distinctive cases, as you can see from the photos, which are covered in a heavy black faux croc pvc. The detailing is as fancy as on the horns, and even includes a tiny cast metal saxophone emblem on the top.
I have seen at least four 1950s/1960s (not sure which) B&S horns for sale on Ebay in exactly the same cases. So, I reason that Guban made fancy cases for B&S and B&S made some equally fancy horns for Guban to put in them and market in Romania.
As I say, speculation - but I look forward to reading other people's theories - or better still, firm information!