While shopping the aisles of Costco, you may have seen its Kirkland brand balsamic vinegar and thought it would pair perfectly with your next salad or a fresh loaf of bread. And you'd be right.

Attention, chefs. There's a newcomer to Costco's shelves: Kirkland Signature Organic Modena Balsamic Vinegar, sold online in two-packs of 33.8-ounce bottles with a price tag of $44.99, though some ...