Amazon offers the Angelcare Baby Movement and Sound Monitor (pictured), model no. 401-A-US-1GV, for $48.79 with free shipping. That's the best deal we've seen for this monitor and a current in-stock low of $40. This baby monitor will sound an alarm if no movement is detected after 20 seconds. It includes a sensor pad, parent unit, nursery unit with nightlight, and four rechargeable AAA batteries for the parent unit. (The nursery unit can also run on batteries, but none are included.)

Note the Angelcare Movement and Sound Monitor Deluxe Plus, model no. 401-A-2P-US-2SB, is also available for $79.53 with free shipping. That's the lowest total price we could find by $12. It includes two sensor pads and two parent units.