I've had very good luck with..."The Gun Works"... infothegunworks.com In Springfield OR I ordered 3 dozen last time, uniformly knapped , and I believe they were hand sorted.
As a sidebar, experts say that the best flints are a uniform gray. Don't believe it, I received about 20% that had a lot of cream color and some brown, doubting, I went ahead and tried them. Amazing, 50 or 60 strikes. My frizzen is really hard, sawn flints barely work, the frizzen just destroys them. My lock is an odd size for a .54 and I gave the lady, Suzy, the ideal dimension, and that's what I got. Not the cheapest, but the best I've had 30 years of flintlock competition.

Well this is a fine pickle we're in, should'a listened to Joe McCarthy and George Orwell I guess.