First post, so here goes:
I bought one of these a while ago and they are now reduced to just £8.
This is a full PIR flood light, but it comes with an energy saving bulb that uses just 24w instead of the usual 500w.
This bulb alone costs £9.98 at Toolstation.
You can also use the light with a standard 500w bulb, or buy it and put the bulb in an existing light and keep the lamp as a spare.
It claims the 24w buld is equivalent to a 500w one. However, I have this in my garden in place of an old 500w one and I have to say it's not as bright and takes a short while to reach full tilt. But then it gives enough light for what I need as the old 500w was a bit over the top.
At the end of the day, you are saving 475w of power, so it's makes a saving on the electric bill.