Hi, Saigaless lurker here so no familiarity with mounting a scope on a Saiga but plenty with scopes in general. If you're on a budget for scopes, I'd recommend you go with quality over features. In less expensive scopes, fixed powers generally have the edge in optical clarity and durability. For $100, it's tough to go wrong with something like the Nikon Prostaff 4X. If you can spend $200, you are in Leupold VXI territory and will get a very durable scope with a great warranty. Game can be shot at pretty long distances with a 4X scope and a 9X at the upper end will get all you need out of a .30
