Since you guys have already been more than exhaustive

there are very few things more I can add about Balsamico...
As you said, the real Aceto Balsamico can have on its label two possible definitions: "Aceto Balsamico di Modena" or "Aceto Balsamico Tradizionale di Modena" both allowed by a specific Consortium and followed by a progressive number.
Sadly, none of those definitions guarantee a good quality by itself, since Aceto Balsamico is not protected by a DOC (Denominazione d'Origine Controllata) which is, in Italy, the only certification which ensures to a food product its original features and a really high qualitative standard.
So, also the bad or ordinary stuff can exhibit the same numbered label of the top products. More, the same producer can make many different Balsamics with a different quality...this is, in example, the case of Fini and Monari Federzoni, that sell excellent Balsamico and awful stuff for suckers as well

I can't suggest to you any label for two reasons...the first is that I don't know which brands are available in US, and the second is that I buy only average products for cooking as I always get the "real" product as a present from a family of friends which has been making it for 100 years at home
The only advice I could give you (but many of you already know it) is that the really good balsamico is VERY expensive, up to $30-40 for a small bottle...so, if it's cheap it's not the real one but normal vinegar mixed with must and colored with caramel
Only your palate can judge!
BTW: The word "Balsamico", although coming from the Greek (with the meaning zouzouni explained) in Italian is usually meant as "Aromatic, intensely flavoured" and sometimes "giving benefit to your health": i.e. another thing that is typically "Balsamic" are the sugar drops for sore throat ("Caramelle Balsamiche") which obviously are not intended for culinary use
Pongi