Found these at Bunnings Lidcombe (near CostCo) in Sydney - I bought 4 for Xmas gifts!
They have a short flex and bayonet plug, so you can DIY install into a standard lighting socket.
Even use them for spare parts, or use the bulbs & gaskets then chuck the rest away :-)
Not sure if they are at all Bunnings stores, they were in a big pile on an end in the lighting section. They're probably a run-out because of the 150W bulbs (I think they are now defunct under MEPS, replaced by mandatory lower wattage), but doesn't matter for this price.
Here is the instructions PDF which has the pictures, dimensions etc
http://www.arlec.com.au/wtyFiles/MAL435/MAL435.pdf
The new model at Bunnings is this one, which looks the same and is $29.90
http://www.bunnings.com.au/products_product_light-security-f…
To install you just screw them up onto the surface and plug it into a standard Bayonet socket. Adjust the angles of the heads and PIR, then set the PIR sensor's settings for time, sensitivity, light level, etc.
Alternatively, the flex and plug can be removed and the unit hard-wired by an electrician.
Yeah, they are halogen incandescent lamps and not very energy efficient, but the price is right. Perfect if you need something cheap and cheerful to light up the side passage. Or up the rear passage, if you are that way inclined :-D
Geeeez!! just saw the same item yesterday afternoon at Bunnings (in Melbourne) for $19.98