Funnily enough I just noticed the same. I have had a long break from shooting, and just dusted off my lovely BSA Superten BBK. I'm currently helping a friend buy an air rifle and found lots of R10's for sale, wondered the same. I must say my S10 is going strong and never missed a beat.
Edit: 2 posts down a long thread about leaky R10's!
Good deals: Greylag, Blade, Tankbanger, PodgyBear, Godwin, gt550a, Stereotype, Dwazzer, Paul1952, Benchrest, Steelyglint, PaulsOK, IronMonkey, Verminator66, Lupus, SonOfDave BSA Superten BBK .22, Theoben Evo T/H .22