Hi Ian, and welcome to the club.
What I am going to tell you could be very useful but also a little difficult.
My s type keys were causing a little problem, and,as you say, would be a bit costly to repair.
I live in Sutton Coldfield - Birmingham - and I went to a local engineer & locksmith who managed to "invent" two keys for me for £100 after they checked my electrical part of the car.
Duplicat Vehicle Locksmiths can be looked at in the Internet. Just tell me if this is of use.
Regards,
Peter.