I first tasted real balsamic vinegar at a specialty shop for olive oils and balsamic vinegars in Oak Park, IL, when I was visiting my brother and his family about 10 years ago. I bought it from them online till a shop opened locally; that one recently opened a third location pretty near to me, so I get it there now. Their balsamic vinegars are made in Modena, Italy; the website says it's "aged up to 18 years." The minimum is 12 years, so it's not the top-shelf stuff, but it's very good
It's $33.99 for a 750-ml bottle, although they give you a discount for bringing back and refilling the bottles.
I love the stuff. I also have a few flavored balsamics, and a white balsamic. I was so proud of myself yesterday! I went to lunch with a friend yesterday at a restaurant right by the shop. We went in to taste and I didn't buy anything!
I bought Gravenstein apple flavored balsamic a couple weeks ago and I don't need more right now.
In case you want to drool a little: Savor the Olive
Strawberry balsamic vinegar is incredible over chocolate ice cream