There's no substitute for saba or aged balsamic vinegar, but I discovered a way to use ordinary balsamic vinegar and increase its flavor.
Buy the cheapest balsamic you can find. At a restaurant supply store like Smart and Final, you can buy a gallon of balsamic vinegar for under $20.00.
Pour the vinegar into a large pot and put on the lowest flame possible. To avoid a "cooked" flavor, all you want to do is accelerate evaporation.
A gallon of vinegar will take 10-15 hours to reduce the balsamic to 20% of the original volume. Taste the vinegar. You're done when it has a slightly sweet flavor.
Wet a piece of cheese cloth and put it inside a funnel. To get rid of any solids that might have built up, pour the reduced balsamic through the cheese cloth. Pour the "syrup" into squeeze bottles, the kind you…