Dude, it's not so hard. Find a box at your office that fits, or go buy a mirror box from a moving store, UPS/FedEx store, whatever. Then, if your glazing is real glass, put a tic-tac-toe board of the really expensive blue masking tape on there in case there's a crack in shipping. Then, slip the frame into a polybag (or trash bag if you have to) and tape that closed real nice. Bubble wrap that bastard real good, slip all that into the box with a bunch of peanuts. No problem.
But a serious bump can still dislodge whatever mounting system you used, so, nothing's perfect. But you'll be fine.