Create Joomla extension, savings calculator from Excel

Hi Joomla EXPERTS! We require an excel spreadsheet (Energy Savings Calculator) to be converted into a Joomla extension. The spreadsheet contains formulas for calculations. No macros. The spreadsheet contains configurable parameters, which will need to be available in the Joomla CMS. - Integration with Virtuemart products table, where the calculator is configurable for each product page (set in CMS). - The user will have the ability to add product quantities to shopping cart from our site, we would like calculation to be shown based on product quantities selected. Eg, customer selects a quantity of 2, the calculator updates its output according to the selected quantity. An excellent developer required with excellent communication skills. This project may lead to further work for the winning bidder. The lowest bid may not necessarily win the work. Please write a small message to sell your abilities and skills, including previous work samples and feedback. Please let me know cost of development and total time (elapsed days) / date of completion. Thanks, Jamie