I used to have a German friend who had a regular Sunday night spot in a London pub playing one of these, very similar to one of the instruments in Mark Clark's link. He was a wonderful and very versatile player and could play a great variety of types of music on the zither. Needless to say, The Third Man tunes were very popular with the regulars.

Regarding value, these instruments don't really command the prices they deserve as instruments because they are somwhat out of fashion (except in Germany, Bavaria and Austria!). Price would depend on the appointments and quality of build but I would say you definitely have room for negotiation with the antique shop Max. If you do buy it, I think you would find it both challenging and rewarding.

I've restored a few of these and restringing is almost always necessary. The gauges used are within the guitar string range and I would match up by taking a micrometer comparison with what's already on. You'll most likely have to "de-ball" the stings unless you have a handy supplier of loop-ended singles.

Peace,

moo