Someone told me in 2005 when I was starting my Releve' dance poster business that dance teachers we not online yet, they were slow adopters. Well, that may have been the case in 2005, but it's all changed now. I'm hoping that all dance teachers now have access to the web and are using it to build their business and communicate with their clients. If you don't have a site yet, there are many places to go. I did a very simple site for my studio using http://www.vistaprint.com/, give it a try.
I've encountered a few sites I thought I'd share with you...
Dance Advantage http://danceadvantage.net/
Dance Advantage Interactive Companion Network http://danceadvantage.ning.com/
http://www.zazzle.com/ - you can build a shop and have logoed items to sell to your dancers.
http://www.gendance.com/ - for the hip dance crowd
http://www.danceteacherweb.com/- a paid subscription site, but worth the price.
http://www.danceartfx.com/- t-shirts,tickets and more for your shows.
There are thousands of other sites, if you have one you like post it in the comments and share it!