My website is
Math Celebrity™ - Building Sizzling Hot Math Skills
For 4.5 years, we have been free. But because so many people over the last 2 years have asked us why we are NOT charging, we decided to go commercial. The people we have spoken with helped us set our prices.
Essentially, you enter a math problem, push the button, and every single line of math work appears. Example: Enter 19876/432 into the search engine. Based on the amount per hour you spend on a tutor, the amount of detail that they show you, coupled with the fact that they are only available certain hours of the day, we felt that it was the right time to start charging.
When school returns, we will hit 35,000 visitors at minimum, and my hope is 500 of those consistently pay the $20.00 monthly license fee, all access.
There are a few other services I know of that friends or colleagues have that are free now, but t hey wish to charge in the future. I use my site as the guinea pig for this discussion.