Good/ Reputable store in NY for 2nd hand tenor sax?

There are quite a few nice stores in NYC, but be prepared because everything is expensive compared to the standard online prices. Maybe check out Sam Ash on 48th St. or Robertos, though a slightly cheaper alternative may be to go to USA Horn in NJ.

As for tenor saxes in this price range, it depends whether you're looking for modern or vintage; for modern, you can probably try out any demo or "slightly used" Yamahas, Yanagisawas, and certain models of/slightly older/more used Keilwerths and Selmers. For vintage, you just about have your choice for top vintage American tenors, as well as some French tenors, such as Buffets and SML's. Also, don't discount vintage Keilwerths, which are really a great deal.

Hope this helps!

There is a cluster of music stores which sell saxophones in midtown Manhattan.
In no particular order:

Manny's Music: 156 West 48th Street
New York Woodwind and Brass Music: 168(?) W.48th street (not sure this is right)
Roberto's Winds: 149 West 46th Street (http://www.robertoswoodwind.com/)
Sam Ash: 160 W 48th Street

I would suggest you bring your reeds and mouthpiece (assuming you have one already) and try some of the horns at these places. Don't just trust them, play several different horns.