Automated Quoting System

We have a website with a php form that emails us information that users fill out, with that information we give values and email quotes to the user. We would like to automate this process rather than getting email involved and would like to use an xml database to store the values. When a user picks the item they have, they would then need to pick from a list of problems that could be wrong with the item which based on the values we put in the database would take the value down, once they have filled out all of the options the system should give them a value instantly. I need someone to write the script and program it for us. The database that it uses needs to be impossible to get at by competitors but needs to be easy to edit so we can constantly edit the values on a week to week basis. New to this so let me know if I left anything out or you have any questions