Barry,
As someone who had developed a rather complex
database application to help manage various aspects of a public water/wastewater utility, I generally tend to discourage doing it on your own without a fair amount of support. I had a friend who owned a computer shop and he had a sign on his counter that said customers have a right to any two of the following through: fast, cheap, and good. If you have a lot of money (or other resources) you can usually develop something reasonably quickly and pretty good (or pay someone else to do it). If you have a lot of time you can usually develop something reasonably good and cheap for yourself. If you do not care too much about quailty you can usually piece something together for yourself cheaply and quickly. I'm not sure what your reasons would be for using Filemaker (back in the day I used Paradox and wanted to move toward
Oracle - before I became a big fan of open source), but I might consider one of the databases that works with Moodle (n.b. I'm assuming Filemaker would not but do not know this for a fact since I've not worked with it). It is convenient if you can have one common database server and all of your data there. In addition, then you could work on having some integration between the two systems pretty easily.
I've been following with interest the development of SISs and most of the open source ones do not appear to be mature enough for prime time. That said, perhaps getting a few more folks working on development would be helpful. I personally believe that the open source model provides a way of breaking through my friend's fast, cheap, good limitation. I think you can develop software that is fast, cheap, and good if you collaborate well with others. So if I were in your shoes I would be thinking of either joining an existing project and set my folks to work on building it up and getting it up to standards that you would like or possibly even starting your own project. I think working in community (perhaps with folks found at
http://sis.akedu.us/ - which I just found doing a quick Google search) might be a good way to go. I might start by looking at
http://www.schoolforge.net/education-software/web-based-student-information-systems-sis and seeing if there are any of those that you wish to get involved with. Keep me posted what you decide and feel free to let me know if you have other questions.
Peace - Anthony
p.s. - Another site listing some open source SISs is at
http://schoolcomputing.wikia.com/wiki/Student_Information_Systems
