For home brew, Lowes has (had?) a 4 AA battery operated motion sensor night light for $15. The AmerTac brand with the CDS cell on top uses a lot less total power, because in daylight it shuts the whole unit off, so the light won't light and the motion sensor is not looking for motion. Daylight power consumption is <1ma, IIRC. Cheaper than buying the parts in it!
G-