Where are you operating from Bluebeard ? The strip I operate from is right under Luton Zone and they are happy to accept non transponder equipped aircraft. Are you planning to operate into the Channel Islands on a regular basis?
There is a fan driven generator available to PFA type aircraft which will give you more than enough power to run a transponder. Çan't fit one to a Tiger or an Auster though without reams of expensive paperwork being generated also.
PS Unless the PFA, AOPA etc are successful, we will all have to use Mode S in the not to distant future..........