The addon camera that's strictly the camera is only $5 cheaper than the 1 camera kit which comes with the bridge. So you can do a 5 pack + 1 camera pack, for 6 cameras and 2 bridges for 2 houses.
I wanted to get a second camera and noticed why not pay $5 more for the bridge in case i want to split them up for whatever reason or if my current one stops working, $5 more is worth it.
Could also do 3 camera kit + 1 camera kit, for 4 cameras and 2 bridges too, depending on how many cameras you want.