what is the average monthly price for adt
ADT Home Security Systems Sample Costs. 1  A basic ADT alarm system might cost around $100-$350 to install if you agree to a 36-month monitoring plan that about $35 per month. A system at this price might include 1 control panel, 3 door/window sensors, 1 motion detector, 1 built-in siren, and a keychain remote. ADT monthly monitoring fees start at $32.95 per month for basic security. Additional monitoring for smoke, fire, water, etc. cost extra. A package with 7-10 window/door sensors, 1 motion detector, 1 control panel, a siren, and more might cost around $500-$700 to install, plus monitoring fees.