Need to know pricing for replacing a timing belt on a 1967 Olds 98?

The car is already in the shop getting the oil pan and trans gaskets replaced along with brakes and front suspension, so many parts are already off the car and the timing chain is already in reach. How much in fairness extra should the timing chain and timing chain cover cost to replace, looking on e-bay the costs on the parts are approx $100.00. I just don't want to be taken advantage of on the labor especially when he is already working in that area and charging me labor.