I'm in Swindon and do them for £35 a seat. Did mine 2 years ago now when I first got the RR (as the seats were out to re-trim the vehicle with black carpet, heater core.. and the rest.. )
I extended the wires to run underneath the metal retaining rod so it doesn't get squished.
Drop me a PM if you're interested - though I'm not about until mid-March now (got to go away for my 'real' job!)
Cheers,
Marty