£30 delivered. I've only ever made brushed stainless panels but have then powder coat black and blue previously. Although I wouldn't intend on powder coating again.
There's a place near ibrox that might be able to help. http://www.glasgowturbos.co.uk/ They will most likely need to strip it to diagnose fully. Is there definitely no play in the shaft?
I doubt you will be able to bolt these to the OE rails and maintain sliding adjustment. Maybe better sourcing a steel set and get them welded to the rails.
No need to re-register as daniel_g says, it's UK As long as the seller sends the log book away, it should automatically be transferred from DVLANI to DVLA (I think)