Let's say you have 1 Build per Class, Per Mode. Strikes NF Crucible Trials Gambit Raid That's 5 PCs per Character (if 3) so total Minimum of 90 Armor PCs (assuming you use different class ones) Now, the only Multiple Builds I see are for Raids, since they give Extra slots for mods. So you would have more. I'd say for all armor and raids, minimum you really need 200, Just for Basic Loadouts. A casual player would need less. As for weapons, You can easily disregard most exotics once they go to your collection. I typically only have the ones I use the most or am working on catalysts for. So Exotic Weapons can be dismantled and pull out when ever and just infused back to lvl. Exotic Armor is a different story and most are kept due to stats. So, overall 400 seems just right. That leaves 200 for whatever else.