Got it at CW in Statesville. You can buy them online as well. I got mine for $20 but I had a gift certificate that CW sent me and a $5 off the shower head from the GS coupons (member). I think they run anywhere from about $30 on up, depending on where you buy it. Bought ours at CW because we are only about 8 miles away. Saved on shipping.
For the best results, do it navy shower style. Rinse, turn off. Lather up and rinse again. Hair, the same way or if you want to do it all at one time. Don't let the water run continuously. Use the little shut off button. My wife has long hair and shaves her legs in the shower, so there is a little extra consumption there.