The original true balsamic vinegar is not really a viable commercial product. When someone started a new batch, they rarely lived long enough to see it to completion for it took a minimum of fifty years to develop fully, sometimes even seventy-five years or more. It is made by first cooking down the must (partially fermented grapes) of the white Trebbiano grape. After it is allowed to turn into vinegar, it begins its journey through a series of five increasingly smaller barrels made of different kinds of wood, the last always being juniper. The vinegar spends five years in each barrel, becoming more and more concentrated. Finally, it is transferred to the aging barrels, where it remains for twenty-five years or more. Obviously, this is not what you find in half-liter bottles costing less than ten dollars. The closest thing to real balsamic vinegar is sold in perfume-sized bottles whose price is never less than three digits. Only a few drops of that precious liquid is necessary to enhance a salad or finish a dish. Otherwise, look for bottles that are around 8 ounces and sell for twenty-five to forty dollars. Although they could not be mistaken for the real thing, they approximate it well enough and are what I recommend for recipes that call for balsamic vinegar.