A few years ago I decided to invest in a juicer...that was before I knew about the Vita-Mix! I still break it out a few times a month on the weekends and make carrot juice, adding in greens and fruits depending on what I have on hand. I love homemade juice because you never have to add sweetener, you can sweeten with real fruits and you know exactly how fresh they are! You also get the benefit of added nutrition, fiber and enzymes from the raw produce.
Most commercially made juice has been pasteurized, meaning it's been cooked at low temperatures to kill bacteria. And who knows what condition the fruit was in that was used, or how long the juice was sitting on the shelf at the store before you bought it?
I think it's okay to use store bought juice on occasion, not as an everyday habit, so long as it is organic. But if you really want the health benefits of drinking juice, you really need to make it at home! It's a great activity for the kids to be involved in too. Younger kids can help feed the veggies and fruits into the top of the juicer and older kids can also help with chopping the fruits and veggies.
I recommend any of the Omega Juicers. They are super easy to use and clean up is a breeze. These juicers also press the juice and none of it gets near the engine where it could become warmed.