I saw that ad and it really seems like a speculation advertisement....seeing if anyone out there will bite. I imagine they're looking for a best offer.
They claim its one of 5 known UNC's ...so that's more than we thought was out there (most collectors I've talked to only suspected an AU to UNC but not gem). This makes one wonder where these gems came from. For me, it actually puts a cloud of doubt as to the existence of gems, and to the whole numbers of survived notes.
Maybe I'm all wrong about this...but I would think that they're asking about twice what one should be asking for such a note (more around $2500) in search of a very high best offer. I have to admit that if I did have a lot of spare coin then I would be tempted (to at least make an offer). But, alas, its out of my ballpark.