It IS a lot of money. But air bags and air hitches are two different beasts.
Air bags will not isolate the trailer from the truck like an air hitch does. Air hitches absorb truck jolts and bounces without passing them along to the trailer. And they do the same thing in reverse - absorbing trailer bounces that would be passed along to the truck. Try to visualize the hitchpin resting on a big pillow.
I have a Hensley BD3 and also a Mor/Ryde pinbox and between the air hitch and the pinbox, I enjoy a mostly smooth ride, even over rough roads.