“We have been quoted £1000+ to fit it”
If your machine is going to join the ranks of the PFA then you should save almost all the £1000 fit cost by doing most if not all the work yourself. Unfortunately, you will have to get a move on as I think there is a deadline of March 08 for fitting mode a/c transponders. After this, if you fit anything it has to be Mode s.
You will have to get a PFA inspector to sigh the work off and pay the PFA £22.50 for a mod (which will have to be approved in advance).
Rod1