Isabella's Islay holds the title of world's most expensive whisky, and it does so by a mile—well, technically by about 6 million dollars. While the cask-strength scotch inside is reportedly very good (though what self-respecting drinker would speak ill of a spirit they bought with the equivalent of a Beverly Hills mansion?), most of what you're paying for is the bottle.
The English crystal decanter is emblazoned with over 8,500 diamonds, 300 rubies (they spell out the name, which can be customized), and the equivalent of two bars of white gold. There's very little information available about the whisky itself, which indicates to us that this is really just an excuse to show off the size of your bank account. But hey, if you can afford it, more power to ya.