Alex is an honest dealer. I have purchased 7 Russian rangefinders from him and have never been disappointed. I would rather pay a little more from a trustworthy man then get a cheapo that looks like it was smuggled out of the C.C.C.P in the belly of a goat.
My best source of information on collectable rangefinders has been Matts Classic Rangefinders and Compacts. Great site, super guy.
PSo not forget that Rule #1 with those old Russian cameras is..ALWAYS COCK THE SHUTTER BEFORE ADJUSTING THE SPEEDS.