This is essentially a Polish-language version of eBay.
Now, I can’t speak Polish, but Google Chrome and Iron (the non-Google-branded version of Chrome) do have built-in Google Translate functions, so you can navigate fairly easily. The musical instruments section is http://www.allegro.pl/9498_instrumenty_instrumenty_dete.html and, if you’re just looking for saxophones, you go to the subsection that Google Translate amusingly renders as “Tin”.
The thing that I found interesting is how many older Weltklang horns were on sale there. Weltklang was the forerunner of B&S and their horns were produced in Est Germany, so I suppose it’s somewhat logical that if you’re in Poland, the most common “vintage” instruments would be East German, as West German instruments would have been made by Capitalist dogs :).