That is priority of buying and I am doing that now, heavy on primers and powder.
www.thegatewaypundit.com
How many pieces of brass for each do you have and how many times do you plan on reloading each? 1 to 1 for primers and bullets just to be able to use what you have. As to powder, usable case capacity divided into 7000 will give you the number of reloads per pound of powder (and likely a small amount of excess powder). Those would be your minimums if wanting to use all of what you have to your planned usage.
I started with a Dillon 550 so I've never bought less than 1000. In the early 90's 1000 Winchester primers were in the $11-12 range. A splurge purchase at a fun show would be a "sleeve" of 5000 for $50 and save a few bucks.
This helps, I can use this to model it out better. My first idea was just use the max grains for a typical load find an average and then extend the other components and add in brass life to brass on hand.
The only issue with that strategy is with those of us shooting for long range accuracy and competing. Mix-and-Match supplies make it harder to keep and manage an optimal cartridge made with consistent components ... but using what you can get is admittedly part of the game lately.
Yeah I try to keep enough of everything for a few barrels worth and buy it in that quantity. I like to have 2k bullets for each of my main calibers of Berger that can be hard to find and I only use a few different powders so it's easy to keep at least 16lbs around. I've been waiting to get more components for a while thinking the crappy economy would cause some prices to go down but that may not happen before the war shortages cause low supply
