I would suggest asking on the mobile portland google group. Suggest it be built on the cheap with a cross mobile OS framework. You will save $ if you have the app UX mapped in advance.
You might also talk to local startup Surveymonkey. They are more set up for anonymity, while you would like to track an individual over time. May be a use case they haven't thought of. Never hurts to ask though. Maybe send clients a txt each day to engage the survey.
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