I'm not a collector per se, I suppose, but I do look for and buy neat-looking boxes of older cartridges, my requirements are a full box, and really nice condition of the box. Got about 40 boxes, ranging from old .22LR and a nice minty .22 Hornet, up to a Martini-Henry packet of 10 rounds from the Zulu War. Picked up a box of Remington 6.5mm Mannlicher-Schoenauer last month, that was kind of neat, and found some great African calibers last year in Kynoch and Winchester boxes. The military stuff is fun to pick up, got a French 7.5 box and some WWII pistol rounds from several countries. It'll make a nice display once I find a curio cabinet for it all.