I was charged £46 labour at my local garage, which is one hours work. This was doing it properly, lining up to TDC and checking all the marks.
I found them by accident, they are excellent also.
That was for an 8v, only looked in Haynes but 16v shouldnt be too much more in terms of time?
I would ask people in your area/work about it, usually you can find good garages that way.