Go for it! $10US for 40 minutes is quite cheap but I guess it depends on the area. Be careful, beginners are probably the hardest students you will ever have to teach!

But if you love teaching it is a lot of fun to help them to work on their challenges.
You have to get experience from teaching. something you just cannot learn from a book, so getting this experience has to start somewhere, if you are interested in teaching this can never be too early! Beginner students are good to start with because you can work on things that you know how to do yourself but can be terribly difficult for them. You should be always considering things in terms of how your students think and helping to instill a more musical thought process. This will reveal to you multiple ways in approaching simple situations in music. We might have our own personal approach to it, but when we approach it in terms of the students perspective interconnected with our own teaching method, things can be very different and interesting indeed! I certainly have found it amusing how many different ways someone can read line and space notes in sheet music!!!