LI has a heroin problem. Amber did not have to travel to NYC for a fix. Guess Dave said that so his connection on the Island doesnt get nervous. He was talking to cops and media.
Living on Long Island and knowing enough drug users over the years, I find this to be the more likely explanation.
There's a cost to travelling that much every day that would make the pricing ultimately not worth it. Not to mention the danger of traveling that much with hard drugs every day. Not that a lot of these people are in tip top state of mind to be making totally rational decisions. Otherwise they wouldn't be copping in the first place.