Been going there for years. (I once participated in 18th century reenactments there.) I was there again last weekend.
Among the vendors, there were lots well-made flintlock long rifles available in the $1,200 - $1,500 range. Also the components with which to assemble them. There were few military muskets, or flintlock handguns. The highlight, to me, was a double-barrelled flint shotgun, with full inlays and engraving. (Newly made.) Asking price was $11,500. A little too rich for my blood.
The Market Fair is a really good place to find handcrafted pottery, weaving, woodworking, blacksmithing, etc., made in the 18th century style. Most prices were reasonable.
Something that has always bothered me about Ft. Frederick is that, as it was restored in the 1930's by the Civilian Conservation Corps, it's impossible to be "fought." That is, there are no parapets or firing steps on the inside. The Fort is a square with bastions at each of the corners, and a single gate, with two wooden barracks flanking the parade ground inside. But the outer walls are sheer stone walls about 20-25 feet high. No place for troops to stand to fire over them. (There should at least be a wooden catwalk for this purpose; ideally the bastions should be filled in to provide platforms for artillery.) (It's true that when the Fort was used as a prison camp for Confederate prisoners during the Civil War, the firing platforms would have been on the outside.)
