I gave my tattoo artist a smoking pipe and a tin of tobacco a while back. He is working on my sleeves, and we have talked quite a bit while he has tattooed me. He always takes these little 2 min. smoke breaks to smoke cigs, and I told him that if he liked to smoke, he should try smoking a pipe (again, tobacco, not weed!).
I think as far as gifts go, it depends on the artist and their personality. Some dudes just don't seem like the type to appreciate or want to receive things from their clients. Maybe it would make them feel weird.
I think it just comes down to personal discretion.