I am rather fond of the energy drink. I sip away at the one liter bottle all day at work.
One thing I found that you can enjoy without plunking down the money for the carbonating system itself is the grapefruit flavor. While the temps were in the 90s here I would pour a cap full of the sugar free version into the blender with ice and water. Instant pink grapefruit slushy. Great way to chill after being in the hot sun or having to endure a hot fourth floor apartment sans air conditioning.