I just bought a Russell Hobbs 6 litre one for $49.95 (on special at Target). It's got two sections - one side is 4 litres and the other is 2 litres.

I currently have a Thai green chicken curry in it (recipe taken from slow cooker chatter #12), so will know how it works later tonight when I taste it!

I've used the 4 litre side for this recipe and there's plenty for leftovers.