Don't know if anyone is still looking for info or prices on these....
Whirlpool.net has a few threads on robot vacuums with quite a few differernt opinions. There is such a thing as too much info! Having done a bit of research, I find myself leaning towards the Roboking. Whirlpool is also handy in that a lot of posts will compare prices and that helps if you are able to find a local store that will price match.
There are two models of the Roboking a red and a green one. Probably about the best price I can find is $500 for the green and $630 for the red. I am not sure what the exact differences are. These prices are from the NRMAShop and are member prices, but I vaguely remember some people saying that Harvey Norman was similiar prices.
Hope that helps someone.