not a bad price to do that amount of work. ask if they could do the pair valve mod while they are in there as well.
also, i would ask for the old plugs back, just to make sure they change them.
Being right is bitter-sweet when you're ruled and surrounded by morons.
"Men fight for liberty and win it with hard knocks. Their children, brought up easy, let it slip away again, poor fools. And their grandchildren are once more slaves." - D.H. Lawrence