Group lessons are a fun, inexpensive way to learn the fundamentals of technique. You may not get an in-depth explanation of technical principles but at least you get a nice overview.
Later on, as you improve and acquire more experience, private lessons will be able to help you build on those basic principles you learned in group lessons. For now, I wouldn't worry too much about taking private lessons.
As another option, how about asking the more advanced dancers in your studio or in your dance club to briefly explain some technical principles for you? Not only will that help you, but it will help them too. There's no better way to see how much you know than by teaching others.
You might want to check out various technique workshops offered in your studio. They might run a little more than group lessons, but they're still definitely less expensive than private lessons! And you'll learn a great deal of important technical principles from those workshops!
Best of luck to you,
tango