From similar guns I've seen advertsied on the net, and assuming (a) the lack of case colors and the thinning blue are from use rather than intended and, (b) it still locks up tight and on face and (c) functions properly, it would probably retail in the neighborhod of $500, plus or minus whatever haggle factor you might want to work in.
That price decrement is, IMHO, more from the use and used-looking state it's in, than a lack of inherent quality. The ComBloc German guns were, after all, made by Germans, even though they got a bad rap early on. And the Merkel name got the big jump in price only after reunification.
BTW, I think Merkels at that price are a steal.