I just had mine redone. It's only billed as a half hour labor and they scraped out the silicone and re-sealed it, and they replaced the main valve cover gasket as well since they took the valve cover off to make the job easier. Under my extended powertrain warranty I have a $100 deductible and I'm not so sure that It'll come close to that on my bill which I haven't gotten yet.

They said it's a very easy job and you could probably do it yourself. The biggest problem they had was trying to get the old silicone out of the groove around the sealing surface.