You might as well ask 'How much does it cost to build a road?'. It depends if there is a mountain in the way.

It's impossible to give a simple table of charges for restoration work because each new project is a surprise even to me. All jobs are undertaken to a strict agreement reached before work commences with a full quotation only possible after physically reviewing the material.
As a rough guide: Expect a full audio restoration to CD re-issue standard of a normal good condition LP to cost in the region of 400 GBP - at the highest quality possible. This is MUCH cheaper than you will find elsewhere but I do not cut corners.
Some recent projects have been completed for less, some very complex and difficult projects, considerably more. No 2 projects are the same. We need to talk first!

Remember this: My clients come back to me not for my rates (which are competitive) but because I deliver the project the way the client wants it.