Put a 16x multiple on forward earnings and you get a $45 stock, which is 45% upside from here. Expect company to buy back a lot of stock at this level.
If analysts' estimate of 22.08% EPS growth turns out to be not far off the mark, this is indeed a great bargain. Market is apparently thinking GNC's double-digit growth is now over. But I bet it is wise to buy at this level.