No Idea on costs I'm afraid!
As for Matt, used to know him quite well back in the day (back when he was a Rally driver for MG and Leda supplied him suspension!) IIRC he is based within silverstone itself, I would assume he has changed his phone number since the last time I spoke to him, but I still have his mobile number from 10 years ago... lol
As for quality of his work, I can't say I've heard of anything bad about him... I think he did some work on a few Diesels on here at some point and IIRC they were happy. Plus he's always given me sound advice on the phone