Gone are the days when you made a cocktail by mixing some gin with some tonic.

With the current boom in rarified, often very expensive spirits, you can make your highball with quadruple-distilled gin. Or a variety flavored with lotus leaves and lavender. Or, if you prefer, a handcrafted version from an individually numbered bottle.

But until very recently, if you wanted a worthy partner for your certified organic rye vodka or virgin Trinidadian sugarcane rum, you had to get into muddling, juicing exotic fruits, and creating simple syrup (which isn’t as simple as it sounds). The only alternative was to add your super-premium spirits to a glass of Coke or a store-bought juice or cocktail mix.

Given the modern penchant for taking anything and everything up a notch (or six) on the luxury scale, it’s hardly surprising that several entrepreneurs have started to—ahem—shake things up. They’ve created a new generation of mixers: made with exotic ingredients like organic agave syrup and quinine extracted from Rwandan tree bark, they’re packaged in eye-catching bottles that might resemble anything from old-fashioned soda to expensive bubble bath. And they’re priced accordingly.

Obviously, there’s still no real substitute for a drink made from scratch by a professional. And some bartenders still find many labor-savers too sweet or artificial-tasting. But now there are drink bases so good that even top professionals—who often shun anything pre-made and in some cases go so far as to make their own tonic water—are giving them a try.

One pioneer in the premium-mixer marketplace is Stirrings. The Fall River, Massachusetts, company was founded by friends Gil MacLean and Bill Creelman, who had been selling salts and rubs under the Nantucket Off-Shore label. One day, while making margaritas, they decided to try some of their sea salt on the rims of their glasses. The partners agreed that it was a big improvement over the regular stuff. In 2000, they began selling their own cocktail salt—made from the expensive French sea salt fleur de sel and flavored with lime, basil, and cilantro—the first innovation in a now-extensive line of cocktail garnishes and mixers.

At first, their products were a hard sell. Because wholesalers were skeptical that anyone would spend $10 for a drink mix, Stirrings had to do its own distributing.

“We had to change the way consumers thought about cocktail mixes,” MacLean says. Many of the company’s first offerings, including its apple-martini and Cosmo mixes—made with cane sugar instead of corn syrup, real fruit juice, and triple-filtered water—quickly became hits. Now, Stirrings boasts almost 20 varieties, including bases for mojitos and Bellinis. (A 32-ounce bottle, which makes about 11 drinks, costs between $8 and $10.)

The firm’s annual sales currently top $20 million, and double-digit growth is expected next year. Since last summer, Delta Airlines has been offering in-flight cocktails made with Stirrings products, including highly carbonated sodas meant to keep drinks from going flat (a four-pack costs about $5), as well as syrup, blood-orange bitters, and grenadine.

Stirrings now faces competition from abroad. In 2005, Charles Rolls, the businessman who engineered the rebirth of the Plymouth Gin brand, launched Fever-Tree, a British maker of premium mixers that are being exported to the U.S.

Rolls scoured the globe for Fever-Tree’s ingredients. The water for the brand’s club soda (a four-pack costs about $6) comes from Scottish springs; the ginger ale contains ginger from Ecuador, India, and Nigeria. It took Rolls almost a year to choose a source for the quinine used in his tonic and bitter lemon. He finally found what he wanted in the Rwanda-Congo border region. “We’re trying to make the best,” he says. The line is already a hit in Europe, where it’s used in some 500 restaurants and bars, including such renowned establishments as El Bulli, in Spain, and the Fat Duck, Nobu, and Claridge’s hotel, in England. A number of American establishments, including Cyrus, Bix, and Bourbon & Branch, have also started ordering Fever-Tree. As a result, the firm expects worldwide sales of $4 million in 2007, up from $1 million last year.

One new contender is even touting potential benefits to the waistline: Q Tonic, which officially launches in July, has been appearing behind the bar since May in exclusive spots like Milk & Honey and Gramercy Tavern, in New York City. The brand consists of just one product, a tonic water (a four-pack costs $10). Like its competitors, Q Tonic boasts all-natural ingredients, including quinine extracted from hand-picked Peruvian Andes tree bark and organic agave syrup, which serves as a sweetener.

“The agave matches the sharpness of the quinine,” says company founder Jordan Silbert. Because Q Tonic doesn’t contain high-fructose corn syrup, it has far fewer calories than many other tonics. This is no accident: Silbert says he got the idea for the formulation after realizing that the tonic he usually used in cocktails had as many calories as cola. To compensate, he used to cut his tonic with calorie-free club soda. Now, when he makes a gin and tonic, he uses less gin and more tonic—his own, of course.