I have a Filemaker Pro based app I wrote that works just fine and if you want to do a web based management app I suggest a CMS platform like Joomla. It's free and relatively easy to learn and use and if you like to create... code... and stuff.... allot of fun.
The Filemaker Pro is the best program that I've used. It works for an expanding school population, can segregate billing and stats for dojo management tasks, and is pretty user friendly. I'd never considered
writing my own program, that's beyond my pail, as it were.