I bought a Stack-On from Dick's a few years ago. It's not very heavy and not terribly secure but would at least slow a thief down a bit plus there is a motion sensor in the room with it. We keep laptop, medication, camera, important papers, which are also inside a fire resistant lockbox, and some other things in it. It came with the hardware to bolt it to the floor or wall. I didn't want to screw up the floor so i bought some 2x12's and built a base for it and then filled that will concrete and sunk the bolts in the concrete. That added about 225 lbs so it would be nearly impossible to carry it out.
The only problem is that now that it sits a foot higher my short wife is always asking me to come open it for her since she can't the the dial!