Custom google app

Hi, I would like a custom developed google app that will track the changes made to the google calendar. It will need to track the following: *Addition of appointment *Reallocation of appointment (to a different date / time) *Deletion of appointment If this information could be could be stored in a spread sheet hosted on google docs that would be ideal. Attached is the ideal format that the tracking sheet would come in. Budget is around $75. Thanks.