Additional Module for Site

I am looking to add a module to an existing website. I need to create a simple database where users can log in, and choose a users. Once in the users page they will do chemical readings for a swimming pool and enter their findings, then they will enter the amount of chemicals that were added to the pool. Then they will be able to track the amount of chemicals added to a swimming pool and the cost. There will need to be a page where they can establish the cost of the chemicals. The user will be able to run reports, by date range, month, year. The reports should show per customer the cost of chemicals and the amount of chemicals used. It should print a profit and loss report. You will need to import the monthly revenue from the customer information page so you can print the profit and loss. I have attached some sample screen shots of a similar tracking sheet so you can get an idea.