I'm not a fan but I ave friends that swear the old version of Yatagan is superior to the current formula. As a general matter you can pick up good finds on vintage designers if you know what you're looking for. The problem is that not all sellers are unsophisticated and they will price d/c scents accordingly. If you see a deal too good to be true it probably is. I've heard stories of fake D&G By Man bottles selling cheap. Contrast that with a shop selling a real bottle for $500. Obviously be prepared to haggle prices, one of the joys of NYC!
If you have tie try to hit Aedes (w.village), the beauty level of Bergdorfs, and the fragrance department of Bendels (both 5th Ave midtown). Quite frankly those spots are a lot better for sniffing then the fragrance district.