But from what I'm seeing, 209 primers cost about $9-$10 per hundred.
I was in Cabelas the other day and they had CCI 209 primers in stock of about $4.95 or so per hundred if I remember correctly.
These were not muzzle loading specific.
Hint, when the first 209 primer muzzleloaders came out, there was no such thing as a "muzzle loading" 209 primer. Everybody just used regular shotshell reloading 209 primers. I kind of suspect they still work well today and they only cost about half as much.