Costco’s wellness supplement section has exploded with premium brands at warehouse prices. From collagen peptides to multivitamins, here are the picks that deliver real results. The Vital Proteins Collagen Peptides, Chocolate, 2 lbs ($34.99, 4,759 reviews) is the collagen gold standard. Nearly five thousand members rave about improved skin, hair, nails, and joint support. The chocolate flavor makes it easy…