Web Application with Excel file for Database

Hi, We have a number of Microsoft Excel files that are updated every week. These files contains the prices of specific products for a number f different shops around the country. We would like to create a nice interface that will allow the user to select his city, in order to see the cheapest products prices and shops in that city. The Excel files must be used as the backend database for the interface and everything will run on a Linux server accessible via a Web site. The Web site will be created by myself using Joomla and MySQL on Linux. Please send me message on the time and cost for this project and explain: 1. In what language/software will you develop this Web interface 2. How the interface will be connected to the Excel files 3. How the Excel files will be updated 4. If you have ever used an Excel file as a database for a Web application 5. Your hourly rate Many thanks in advance.