I deal in high grade world coins with my largest section being German coins. I can say confidently that I have slabbed and sold more top pop German coins than probably anyone else in the world. This includes both an MS69 & PR69 non-moderns. Your coin, while conditionally rare, is not rare. In a PCGS slab there are a couple of more active buyers and I could see it bringing $225-$300. In an NGC slab, figure about $150-$225. This does not mean that PCGS graded world coins bring more, but rather there are a few PCGS-only buyers of certain German coins and the Empire Marks are one of them. As for the availability of these coins in high grades, there are rolls of this type and the 1/2 Mark available - including the better dates. They are not expensive - many times the coins selling for far under Krause catalog - and the coins are generally in pretty nice condition. I've purchased several original rolls of both Marks and 1/2 Marks and most ended up grading MS65-MS67.
I've seen your auctions and you do have some great slabbed inventory. Just wanted to add that with the later date German Empire silvers it's a bit of a struggle to get Krause values. For many coins, the Krause UNC value applies to low mint state coins, but with these it applies to really high mint state coins. Many of the later dates, including lower mintage ones, were hoarded when Germany went to inflated currency and base metal tokens right after WWI. Same story as early 1960's US silver.
He can't answer you, unless he sends a PM - forum rules. But I can help a bit - http://cgi3.ebay.com/ws/eBayISAPI.dll?ViewUserPage&userid=gmarguli I think he used to have a web site, don't know if he still does or not. He'll have to answer by PM. I will say this - I have no problem giving Greg my personal recommendation
I have also bought several coins from Greg. He has probably the most consistently high quality world coin selection around. :thumb: