Most folks will have at LEAST 20 lbs of powder- pref. 40+ lbs and at least 15+ lbs is one of their favorite powders.
I am in the camp that says STOCK UP. When you see things on sale, BUY. When prices go up, look elsewhere. Does Cabelas still have their $19.99/1k primer sale? Buy about 20K+ primers and then go look for powders that you like and find the vendor that has most of them in stock and then make a $600+ order.
The nice thing about powder and primers and EVERYTHING with reloading is the long shelf life. I am still opening powder from mid 1980's...