German 18th century Lauenstein schnapp glasses

I acquired these glasses bidding on eBay in about 2006-2007.
I really didn't know much about them before I bought them but I liked the old look and etching. I contacted an overseas company for more information. This is the letter from them and the offer he made me.
If you have any other information or a difference in opinion please feel free to comment.
"These glasses are German. They are mid to
2nd half of the 18th century. It's difficult putting a precise date on them
date would be C 1770 /80. They were
produced in the north of Germany in a place or general area called
Lauenstein. They are used for drinking schnapps or the like from and the
general German term for glasses of this type is 'stampern' or
'zimmermansglas' or 'kutscherglas'; however these are a specific form known
as 'watchmeister' or 'watchmaster' in English. I'm not quite sure where that
term derives from and whether it is to do with clock makers or guards (the watch);I would think the latter. offered $350.00 for the pair"