After pricing them at a few stores yesterday afternoon while out and about, I stopped at Kmart tonight to pick one up. They had the best price on the real thing (the Waterpik one) by a couple of bucks. Also grabbed a roll of plumber's tape.
Removing the old shower head and installing the new one was exactly as easy as I thought it would be. I now have a six-setting shower head with yummy massage capabilities. :-) Should feel very nice on my neck and shoulders in the morning.