It should be fewer than that if they don't allow for the same color to be in adjacent spots.
If we assume the rules from above (one part color#1, one part color#2, one part color#3, one part color#4, one part color#5, two parts color#6) and add a rule that parts that touch can't have the same color we'd reduce 4320 by 1/6th to 3600.
Example -
Torso - six possible colors
r arm - five possible colors
l arm - four possible colors
r leg - three possible colors
l leg = two possible colors
head - one possible color
saber - five possible colors (can't match r arm)
6*5*4*3*2*1*5=3600
This is it - well done! I totally forgot the fact that if it's say, a Red right arm, then you're definitely NOT going to get a Red Lightsaber blade in the figure. So yeah - for each Right Arm, there are only a total of five possible blade colors.
Ok - so still - with 3600 possible permutations - how on Earth, if ordered two did I end up with two identical ones?!?!!? That's not cool!
The best reasoning I can think of for that to happen is that if these come in cases of six, like the Retro Collection Wave 1 figures did, each case contains 6 x of one permutation and there were a total of 3600 cases produced. That would then mean, there are a grand total of 3600 x 6 = 21,600 of these made - that seems low, but I guess in today's collecting market, that might actually be the right number.
Needless to say, I'm going to do exactly what Jeff is planning on doing, check the Target App on Friday morning, see if my store is showing as having them in stock and head over there in an attempt to score one more so I can at least have a 2nd variant and if by some miracle they show up again online in the Target app/website, I might order it again for a possible 3rd variant, but that would be it.
