Fair price for used ARB?

AS the title suggests on a D30 what is a fair price on a used ARB?I have found a couple of these local was just wondering what everyones opinions are.
I am gearing the 8.25 this weekend and installing a no slip.Have the gears for the d30 just want a selectable in the front but don't have enough for a new one.as always thanks everone.

I paid $350 for the used one I had. It had new seals and came with some extra parts.