I remember researching this to bits and can also vouch for Sierra. The sad truth is that there is no where to get consistently good pricing on LightForce parts. I waited for about 6 months and lucked out with an EBay sale of a pair of 240XGTs for $120 each!
I kept some links on my "accessories" file. Several months ago;
Truck Customizers had the best lamp pricing:
http://www.truckcustomizers.com/category/driving-fog-lights/lightforce.html
Sierra had the best prices for covers (where I bought mine).
In Canada we are screwed. It's better to buy from the States and pay duties than to try and find anything here.
What we really need is someone to set up an expedition shop that specializes in Australian products and would become the one-stop for ARB, Lightforce and all the other neat stuff they make down under.
Ever read this:
http://www.4wdmonthly.com.au/
It's one of a few mags I subscribe to. Great mag!