Through 4/23, buy two Select Vitamins & Supplements and get two free at GNC.com, with prices starting at $3.99 each. Plus, shipping is only $1. This ties with our mention from two weeks ago when we saw a BOGO deal and $1 shipping. Some best bets are to add two of the GNC SuperFoods Kelp for $5.99 and two of the GNC Vitamin B-6 100 for $5.99, which drops your total from $23.96 to $12.98, which works out to $3.25 per bottle shipped to your door. Sales tax is charged in states with GNC retail locations.