Percussion Caps

[JKR]

Unlike flints you can’t find percussion caps laying around on the ground.
I recently reworked a nice little rifle that I built for my wife back in 1975. After going through all my old muzzle loading gear, I couldn’t come up with a single #11 cap.
I did some checking around and it seems they’ve gone the same way as rifle primers.
My question is... Does anyone know where I can buy some, and do they require hazmat shipping like primers?
The rifles lock is a small Siler so I could easily change it over to flint if this cap thing is too annoying!
JKR