WOW!! I really don't know what to tell you , the seller could most likely get 6 hundred for it . You don't see many come up for sale anymore and when they do they are gone fast . I have a 3913nl a Shield 9 plus a CS9, the CS is my constant companion . Since I got the gun it has probably had a case of Montana Gold 124 grn HPs shot through it with out a hiccup . If I see a CS9s come up for sale I will be one of the guys your bidding against , at a LGS it's a immediate buy . If I already owned a CS9s I would try to get a CS9.
I hope this helps .