Here's a link to a NYC orchid blogger who has some good places to check out plants
http://deanstreetorchids.blogspot.co...d-growers.html (the shop in Chinatown often has interesting stuff and their discount rack is amazing, but for species, you will probably need to use an online vendor or take a trip to an actual nearby greenhouse like
Home Page).
As far as I know, all orchids in the US are protected and the digging up of any is illegal-additionally, I've heard that the native ones are extremely hard to adapt when taken from the wild, so it's a lose-lose situation all around.
Also, Longwood Gardens is a good place to go for an amazing show and sale in March (it's about 1.5 hrs from NYC) and also in NJ the Deepcut Society has a very nice sale as well in maybe Feb. Plus there are great orchids at the Brooklyn Botanical Garden and the NYBG in the Bronx. You can check the show schedules on the AOS website.