The engineering,development and marketing cost of the older arms generally was done at a time when product demand was ten to fifteen times greater then today. Current product has a small base of customers that the cost must be recovered on, hence higher prices. Manufacturing cost of the actual arm has never been very high. Given the laws of physics have not changed, most of the newer arms offer little in the way of improvement over the older ones. So, you get little improvement with a new, very expensive arm.
