Yeah, that's a St. Etienne. That is the arsenal that made most of the Charleville muskets and pistols for the French Army. But I've only seen pictures of the martial pistols, they have brass on the butt, and the stock is longer and ends in a brass nosecap that usually loops over the barrel.
And while 1809 is Napoleonic era, MOST french martial arms from that period had "ANIX" or "ANXII" or the like stamped on it, meaning "Year of Napoleon (AN) and the year of his reign (in Roman numerals)"
SO, my guess is this is a different model St. Etienne pistol made for PRIVATE sale, unless it was altered. (Somebody COULD have shortened the stock and removed the brass, I guess...)
I am NOT an expert on French arms, I just have a couple of books
Maybe somebody who speaks French, or knows French guns can translate the markings better, but I'd guess you have a pretty decent example of a typical Napoleonic era flintlock pistol!
As per worth, I'd be making a WAG it would be somewhere between $800 and $1200. But that is JUST a WAG, I think it would be worth your while to get it appraised by someone who KNOWS, like Dixie.
You MIGHT be able to email them the pictures and they might make a stab at it that way... www.dixiegunworks.com