I haven't invested much money or time into single cartridges, but probably have 3-400 ( but there is always more than you think, by looking at them in big boxes )
as far as boxed stuff... the guy at the table next to me every year at the local gun show, sells between $500.00 - $1,000.00 worth of full shot shell boxes, with a couple metallic mixed in, every show... so I know the value on those adds up fast