Delta 3D printer extruder?
My FLSUN Kossel 3D Delta printer ($224) has a bowden extruder. It works really well too.

The main advantage of having one is that it reduces the mass of the hot end. That means less inertia, and it's easier on the driver motors as well. All this leads to (hopefully) greater and more precise control at the extruder tip, and, best of all, faster printing.