I have an oil leak. The dealers diagnostic result was a new vanos hose and seal ring, total $250. A valve cover gasket, total $260, and six hours of labor, total $98/hour. Am I being overcharged? Is this a serious problem? Thanks.

I don't know about the other stuff but a valve cover gasket you could change yourself in half an hour and would cost nothing like $260 to buy. This is not a serious problem as long as you do not let the oil level get too low. I would get another estimate.