When the labor requires you to remove the brake caliper and rotor, he didn't really get hosed on the cost to remove and replace the studs. I'm sure they charged you 30 bucks for 2 studs and nuts when they cost them under 5 bucks, how they make money.

Think about it from a business aspect, they need to make money and everything has a labor rate. Be thankful you didnt get charged a dealership price, likely would have been more.