Interesting website and concept. As I have a 2000 Japanese import which will not be under warranty for a battery pack failure before (or after) 80K miles, I was considering going down the same all electric route when the failure happens.
A couple of points I would make - if you check the Autotrader website on a nationwide basis, you would be able to pick up an Insight now from £5000. Secondly, it may be worthwhile approaching government sponsored alternative energy organisations, such as the Carbon Trust. There may be grants available after 1 April, if you can cope with the beaurocracy.