I get the feeling that the green lightsaber version is going to be the more rare version. The reason being that Mara's lightsaber is supposed to be purple.
I think green was the first version as well. I got the green version from some friends last week, but found the purple at retail today via the same store the others came from. That means the wave of green sabers came through first.
From what I've seen here in Pittsburgh and from what mny fellow local SW collectors have reported in on, the purple varaint is the only one to be found.
So indeed that helps to bolster the case that the green variant is the first/rarer varaint.
Doesn't prove it, but does bolster it.