Hi there....to tell you the truth...there are far fewer quality shops than there used to be since most people buy online.
If you want to catch the most shops in New York, you can go to Eighth Avenue between 23rd and 14th Streets....also don't miss NYC Leatherman on Christopher Street
http://www.theleatherman.com/ 111 Christopher Street . You can try on anything there from clothes, gear and accessories, and it's totally cool...the so called try on area is not so large with very small curtains so be prepared to be mostly in the open...kinda sexy!
https://store.nastypig.com/pages/contact
http://rainbowstation.nyc/
https://chelseaexclusive.com/
https://www.rickowens.eu/en/US/stores/newyork
https://www.jeffreyusa.com/
https://www.yelp.com/biz/london-fetish-new-york
https://romanticdepot.com/manhattan/