My Lyman Great Plains Flintlock is very good. And actually my Lyman Trade Rifle with a 1-48 twist shoots patched ball very good. I have not shot a lot out to 100 yards as I just have a hard time seeing a small target that far. But out to 50 yards.. both are deadly.
The Trade Rifle is normally under $400.00 and if you watch sales they were a little cheaper. The Great Plains Rifles new.. unfortunately like the Thompson Centers are well over $500.00. Unless you're willing to purchase new/used from an auction site.
Also if you are going for just patched ball, consider the .54 caliber. I think they are a more accurate caliber in the patched ball department.