In the upcoming Heritage World and Ancient Coins Platinum Night Auction #3041, a nice Batavian Republic 1805 double ducat will be available for bidding.
Coin has a slight double strike of the digit 8 in the date, which is typical for this date. A specimen being offered for sale is the finest known.
It is NGC graded MS65, certificate number 3749943-008.
You may bid this coin here.
22 August 2015 UPDATE:
The coin is sold for $3,762 = 3,303 EUR (incl. Buyer’s Premium).