The prices at Korin are pretty much the industry standard prices for the brands they sell - Suisin, Masamoto, Nenox, etc... Togiharu (their house brand) has a bunch of affordable quality options plus you get a free initial sharpening with a purchase. As for staff being rude, never seen it and they have no qualms showing you and letting you handle any of the items in the display cases. Never really go deep into their stone selection minus a cheap King finishing stone.
If you want something a bit different check out Gotham West Market -
http://gothamwestmarket.com/ Upscale large format style food court w/ a bunch of sick restaurants with set ups - The Cannibal, El Colmado, Ivan Ramen's Slurp Shop, etc... along with The Brooklyn Kitchen having a store with kitchen goods and some selection of Knives to purchase