Have you checked the local restrictions on owning them? Not sure on NY laws regarding exotics.
I had mine flown to me from their breeder in FL. They are not native to this country, nor are they a well known species so this is going to require some homework.
I would stay away from anyone who does not sit down and go in detail about what owning them will be like. Also anyone who would sell you a single glider, if you want one, you are going to have to buy two joeys. They are very social creatures and have been known to become ill and even die from loneliness living as a single pet. I also paid to have my boy neutered by my breeders vet before my joeys were flown to me.
Make some phone calls to make certain there is a vet who specialize in exotics in your area.