Fair price for a used X2D?

I wonder what people consider would be a faire price for used X2Ds.

I still see some advertised at 6600€ but that's obviously far too close to a new X2D2 (7200€ in EU).

I see some appearing in the low 5000€ and that seems more reasonable to me, although I think the newness and added features of the X2D2 still make the latter more interesting.

What do you think?