Create a small calculator application for Mobile as a WEB-APP

I want a platform independent app, a web based small calculator utility having its own personal url, which i will provide you to host). Functioning : Attached is a PDF illustrating how it works. There are pre made categories which's value user has to enter. Upon entering the field, calculator automatically calculates its cashback value depending on the corresponding % value & will display in next text box. Now, upon clicking on Final Calculation, all cashbacks will be displayed and a form to enter just email id with a custom message. Tell me your price and the time-period as soon as possible. SKype : kreativmaestro