I purchased a pair of FRS 2-way radios for CAD$75/pr from RadioShack. Great for camping to or going to a fair/amusement park to keep in touch with family members.

As a bonus, I take one down to my darkroom while my wife has the other. It doubles as our furnace/laundry room. If the furnace kicks in while my tray washer is running while my exhaust fan is blowing, I can't hear a thing from outside the darkroom door. At least this way my wife can get a hold of me if she needs to.