I just want to say how much I admire all of you for starting your own businesses at such a young age.
The Internet will make your lives much easier. When I was your age (you young whippersnappers! ) the WWW didn't exist, and dialup was all that was available to most consumers. If you have any knowledge of HTML, you should be able to code up a quick-and-dirty web site, then use Paypal to accept payments.
I also suggest that you write up a business plan. It doesn't have to be a huge formal document, but it's a good idea to crunch some numbers and make sure you're not losing money, and it's also a good idea to think about how much time you're planning on spending on this - you don't want your schoolwork to suffer.