Paul,
I concur with your thoughts on whole-house AFCI and earth leakage. It would be like trying to find a needle in a stack of needles!
AFCI's retail in the US for about $30, or roughly the cost of a GFCI breaker. The key to getting the costs down is to get the volumes up. Until the contractor community buys in, and starts installing them in installtions that do not require them by code, the cost will never come down. Code right now mandates for bedroom circuits in new construction. There are 1.5 million new homes built a year. With 3 circuits per bedroom, that's only 4.5 million circuits divided among 4 manufacturers. That is not enough volume to drive down the cost of the electronics.
The irony, of course, is that the homes that need it the most (older homes with old wire) will not have to have it by code.
