When I started reloading in 1979-1980 Primers were $6.99/M and that store is known to high priced.
In 1984-5, I loaded 20,000 223's. The primers I used were CCI Sm Rifle Mags, at $45/5M or $7.99/M. The bullets were Winchester military contract overrun at $7.99/M for top grade 55 grain FMJ/BT. I had bought 21M projectiles and still have that box for a rainy day!
IN 1994, I started buying 3 or 4 1000 primers a month for "A rainy day", prices ran from $6.99/m to a few years later at 10.99/M I ended up with a stash of 80 to 90M plus loading 20-25M rounds a year.
January 2008, a rainy day hit I lost my job! I sold every M of primers that didn't have a "Majic Marker" price written on it. I sold the to a gun store for his current cost. 65M of primers at $12.99/M That paid my winter heating bill plus a few hundred left over.( the store put them on the trade in table at $2 less than current pricing, they were ALL gone in 3 days!)
I still had 15-20M of primer, and started rebuilding my stash in the fall.
I have not bought a primer since 2012 and still have 48M. When the price stabilizes, I will start working on my stash again, or I should say "My kids stash!" The price will be much higher than the $7/M I used to pay! The price will be much lower that the current cost when they are used!
Ivan