Even at the height of 'supercharging madness' the cost was in the region of £7000 and we are talking a few years ago. Given that the price of a second hand standard 260 is approx in the region of £8000 then the addition of a £7000 supercharger was realistic in the sense that the car would probably sell for approx £14000 - £15000 so it wasn't necessarily a waste of money on the part of owners wishing for more power and a more unique car. I don't know what figures you have been quoted but it might be worth talking to Chris at MG Lifestyle who would be the only person at the moment carrying out these conversions and he will be able to give you more up to date information on kits from the US and the potential costs.
If you really want more information you should get your completed questionnaire back to Tim to get full access to the forum, lots of information about supercharging available.

Nich.