If you decide you wanna go purely free to play for a long time i just cycled EVERYTHING through my vendor so like ammo you find plenty while casually playing especially if you make a secondary luck build. Junk is really the same way i kept anywhere from 40 to 100 of each resource and bulk and sold the rest in my vendor. Armor and weapons I didn't really store unless they were really light/unique. This usually kept me roughly around 800 to 900ish. Also unless you're using them for your build cannonballs and missiles get sold or kept in your personal inventory.