Granted, this is not a very expensive glaze (about $4 for 5.07 ounces). But for about the same price, you can make a glaze that has none of those added ingredients (although I do add a little kosher salt to intensify the sweetness). If you have a half hour or less, and a glass or nonreactive (glazed) iron saucepan, you can make some yourself.
Lori K's balsamic glaze
The amount of vinegar to use should be twice the amount your bottle holds. Add a pinch of salt for every 10 ounces of vinegar.
10 ounces balsamic vinegar
Pinch of salt
Bring vinegar to boil in nonreactive saucepan. Add salt. Turn down heat to medium low so that it's still on a low boil. Stir occasionally. In about 15 minutes, check to see if it has reduced by half; if it hasn't, keep it on the heat until it does. Cool and pour into a bottle. Does not need to be refrigerated.