I am lucky. I have a great supply of brass, powder, primers and bullets I have stocked up on over the years for what I shoot. Jacketed bullets are saved for varmint and my big game rifles and over the years I have stocked up on what shoots best out of them. At 75 years young I probably have enough stock to last the rest of my life. I also cast my own bullets for different pistols/rifles. I know you long range marksmen scoff at lead bullets, can't push 'em as fast as you need, but out of my 40-65 and 45-70 that is all I shoot in front of real black powder. I also cast bullets for my old Winchester '92 and '94 and most of my pistols. Now with Hodgdon ceasing production on Goex and Old Eynsford that might hurt. I will keep smokeless powder on hand, but I order what I will be loading in black powder and do not like to store it in-house.
But I always keep my eye out for a "sale".