The piece in question is a copy. It is most likely one of the pieces made by Steinhauer & Lueck after 1957. The ribbon may be original, in which case it would be worth about $1000 by itself, but there is no reason to believe the word of a seller who keeps everything private. I wouldn't do business with him, just on principle.
Stay away from any "pie slice" types that are marked 925, as there is a commonly available reproduction of that type made - and marked - in 925 (sterling) silver.
It seems there is at least one commonly available run-of-the-mill reproduction offered on Ebay every week that is described as "absolutely original" and sells for big money to people just lining up to get fleeced. Just because someone has stamped "W" or "JGuS" or any other maker's mark into a piece does not mean that maker actually made it. Anyone contemplating buying one of these should buy from a reputable source, and consult as many reference sources as they can get their hands on before spending their cash. There are perhaps a few thousand original pieces in existence, but there are probably MILLIONS of reproductions.
Here is another recently sold PLM on Ebay that went for $999. It is described as "100% original" and "pre-1930". It's nothing of the sort. This is a standard, commonly available reproduction that can be had for around $25 retail. That's what Lemony Snicket would call "an unfortunate event.":
http://cgi.ebay.com/ws/eBayISAPI.dll...500440326&rd=1
Tim