I was speaking with a guy today that does all sorts of upholstering usually motor vehicles but does do the odd bike seat. I don't know what his workmanship is like but I know he works on cars like Beemers & Aston Martins to name but a couple. and he was not talking silly money to recover a bike seat, He said he mainly gets requests for lowering seats
but can do all sorts including fancy seats for Harleys we buttons and tassles

His name and address are as follows:
Sean Smith Upholstery
Unit 1 Newtonmore Industrial Estate,
Station Road, Newtonmore, PH20 1AL
tel: 01540670190
He said if any one wants a seat recovered, what to do is send him an e-mail with an image and he will be able to give you an estimated cost. to get his e-mail you will have to phone him first though.