How about a larger defensive sidearm? Something, say, in 9mm on the order of a Glock 19, CZ 75 series, or similar. With space a factor, as well as storage/security (given roommates), a second/larger sidearm and ammo with a suitable smaller safe might be the best options. A decent AMSEC or similar safe could provide for effective storage of valuables, a small number of handguns, ammo, spare mags, could be bolted to the floor/walls.