You can buy full boxes and variety packs at nugonutrition.com. They offer free shipping on orders over $100 and have a "Subscribe & Save" option for monthly discounts.
Nugo Vegan Dark Chocolate Protein Bar, 12g Protein, Variety Pack, 18 ct where to buy nugo bars
Chains like The Vitamin Shoppe and Natural Grocers (Vitamin Cottage) frequently carry the full range, including the Dark and Slim lines. You can buy full boxes and variety packs at nugonutrition
Nugo Vegan Dark Chocolate Protein Bar, 12g Protein, Variety Pack, 18 ct | Costco. Costco Business The Vitamin Shoppe where to buy nugo bars