I agree. It looks and behaves very much like a garf purple bonsai (encrusting, then growing, etc.). When it grows up a little, post another pic.
Did the person you got it from say it was the Garf purple bonsai, or just a purple bonsai? I got a Marshall Island purple bonsai a little over a year ago at a frag swap in Chattanooga and it was a dead wringer for the Garf (had both), but without the lineage, of course.