Come and help us work on [Open Data Kit (ODK)](http://opendatakit.org)! ODK is a set of tools for mobile data collection (think SurveyMonkey, but offline first, and crazy powerful). We have millions of users with do-gooder projects in every country. Over the last decade, ODK projects have generated hundreds of millions of submissions with critical data. Some examples:
If $6/user/month is out of your price range then I'm guessing you need pro-bono work. First try contacting someone at ODK and see if a free app that meets your needs hasn't already been developed and distributed:
Tons of contact leads there. I wouldn't be surprised if someone knows of or has built an app that could at least get you started.
Also, fwiw it doesn't sound like you have to build your own relational database with ODK. And if you did, there's also SQLLite built into Android to consider