Lavender ice cream in NYC
I think there's lavendar ice cream in Sundaes & Cones in the East Village. I haven't tried their lavendar flavor but their tiramisu, chocolate, and banana ice cream were pretty good.
I don't know if you want the honey lavendar gelato from Il Laboratorio de Gelato in the Lower East Side but it's divine! Smooth, creamy and flavorful; the drawback was the price though.
Il Laboratorio de Gelato is worth checking. There's even a chance that's where Craftbar gets it from, if they're not making it in house.
Van Leeuwen has a version.
Victory Garden makes goat soft serve, with only a few flavors at a time, but they sometimes make a lavender.
Lula's and Marlowe & Sons have carried it in the past.
It's a difficult flavor to get right.
I had an amazing lavender gelato at Felidia two Easter's ago and it inspired me to make my own since I could not find it commercially anywhere. I've since made it a few times from a recipe I found on Epicurious and it is wonderful. I can share the recipe with you if you ever feel the need to make some.