I can't remember who (maybe Cooks Illustrated?) did some balsamic tests and believe it or not one of the highest rated ones was Colavita....but only the aged one. I tried it and really like it. Probably not as good as a very expensive one--I still have a couple of those around--but I am happy with it. I think it was around $18.
I buy either Trader Joe glaze or Carandini.