The inside approach can be made easily from pvc pipe, pvc connectors, and a foam piece from your hardware store. There is no sense in paying 80 bucks for something that you can make for less than 10 (and have it work just as well). Take a look at the setup of the "inside approach" next time it's on the golf channel, you should be able to discern how to build it from 3,4 pieces of PVC, a couple of joints and a foam piece. If I ever decide to build one, I'll post how to do it here.
harris_tx