I like Aged Balsamic Vinegar.
Traditional balsamic vinegar is produced from the juice of white grapes, boiled down to approximately 30% which is then fermented with a slow aging process which concentrates the flavours. The flavour intensifies over the years, with the vinegar being stored in wooden casks, becoming sweet, viscous and very concentrated.
None of the product may be withdrawn until the end of the minimum aging period of 12 years. At the end of the aging period (12, 18, or 25 years) a small portion is drawn from the smallest cask and each cask is then topped up with the contents of the preceding (next smallest) cask. Freshly reduced cooked must is added to the largest cask and in every subsequent year the drawing and topping up process is repeated. This process where the product is distributed from the oldest cask and then refilled from the next oldest vintage cask is called solera or in perpetuum.
Consortium-sealed Tradizionale balsamic vinegar 100 ml bottles can cost between US$150 and $400 each.
I want to try some.