HilseeJ, I'm not sure there's cause for alarm. They use different flavorings than you do, that's all...I make several juices that I'd put up against anything sold anywhere, and they all use off the shelf flavorings. A lot of the time, the key is in using flavors that don't seem like they should go together. For example, a touch of Inawera "Wild Strawberry" (which is not quite the same as normal strawberry - it's a lot more tart, doesn't taste nearly as sweet, and has a bit more complexity to it) will bring out raspberry or watermelon flavor incredibly well. That's an expected flavor combination. On the other hand, I did NOT expect lime flavor (again, in sub-1% increments, just a hint) to bring out strawberry as well as it does! There's no lime taste, just a lot more strawberry.
Frankly, it comes down to mixing expertise. Experienced ejuice makers know what flavors to add where for the absolute best flavor. How many revisions of your favorite DIY have you gone through? A certain flavor of mine took 31 tries before it was ready for others to beta test. Revision 47 is where it finalized.