Seems a lot of work to make your own percussion caps.
I stop by Bass Pro and Sportsman's Warehouse on the weekend after work, and quite often they're just getting in new inventory of stuff. Lady behind the counter was stacking up cans of Pyrodex, and some caps, and I asked her why such a small quantity of caps. She said that they (and just about all the retailers) have standing orders for caps, powder and ammo, and whatever arrives on their dock is what they sell. I got a couple of tins of Musket caps, since I have a breechloading rifle that uses musket caps, and just got a musket nipple to fit one of my Investarms Rifles - just to see what a bigger ignition flame will do for accuracy while burning some Pyrodex I got on sale a while back.
So, lately all the stores are clueless about arriving inventory - it pays to either call every week or so, or stop in, since, although the cap shelf is bare one day, it may get filled later in the week.