Today only at GNC, buy four select items for $20 as part of its 4 for $20 Sale. Plus, all items ship for a flat rate of $3.99. At $5.75 per item, that's tied with our mention from May as one of the best second-best multi item deal we've seen from GNC this year. (We saw the same offer with $2.99 flat-rate shipping in April.) Choose from vitamin and mineral supplements, beauty care, and herbs.