dont take it to a paintball place they overcharge plus i don't think they have the adaptors to fill 5 or 10 lb canisters take it to a welding supply place. I take mine to T.W. Smith in brooklyn religiously, mainly cuz its only 4 blocks form my place.
However there is a welding supply place on west 52nd and 12 ave that i used to fill tanks at when i lived in the area i think they are called McKinney Welding supply. great place in the city. There used to be a TW smith in the city too however i think they closed down