I use a small East German military surplus bag I got from CTD. I made a bulk purchase of them with some family and friends. I bought 10 of them for my family of four so we could use them as 72 hour kit bags and then a couple extras. They are real durable and CHEAP.
They are not too big though. I really only use them for mags, ammo, eyes and ears, stapler, targets, tape & Gerber multitool. The guns have a different case for each long gun and a double decker case for the pistols.