Pretty muchany decent LFS should have a good stock of 1-3" green sevs. And i agree, tnhey are great fish! Very relaxed, but with lots of personality, and they get nice and big. The only green i have at the moment is a female, so she is only about 6", but she is growning nicely. I think you would be very happy with one.
you can even go with gold sevs or Rokteil. I currently have 2 Green Sevs 1 Gold Sev and 2 Rokteil Sevs in a 180 and it makes a HELL of a show tank. Very awesome fish to keep.