For mobile fitting I used Edintyres (can't recall the number, but google will find him) to do my winters last year - also has a place at Loanhead I think.
Very professional and fair price, although I can't recall exactly how much.
I've used Farmers at Craigleith a number of times and will continue to do so. They've replaced tyres, checked balance and looked at brakes. Some times they've not even charged for the checks despite taking half an hour when people are waiting.
