The addamotor is cheaper than the Foys, which I have, by about $80 if you get their battery solar charger timer pack, which together with the door is $160. The complete Foys set up is about $240, because you have to buy the door to get their warranty. The door is nice though, and works well with their unit. The Foys is powered by double AA batteries and I haven't had to change them in about 6 months, so its an easy unit to maintain. I would imagine you would have to replace the 12 volt battery every couple of years for the addamotor, which would be additional cost. The photocell on the Foys works well and you don't have to change a timer with the seasons. Someone mentioned their addamotor broke after a few months because their door was 6 lbs, not the four or less suggested by the company.