There were several varieties of German made single action revolvers imported in the 50's and 60's. Some were pretty good like the Virginian Dragoon, others were just so-so. If yours is a better one that is all steel then it's probably worth around $150 in very good condition. If it's one of the cheaper ones made with an alloy frame and barrel with steel sleeve, probably $75-125, again depending on condition. The alloy framed guns were plated, and once the plating starts chipping off they look terrible.