Create a simple HTML / PHP form

I need to get a simple HTML / PHP form designed that will calculate a price and then pass it to Worldpay gateway for processing. I only need the form to have the following: - One drop down selection field with price options ($90, $100, $110 ... $150). - One check box, this will add an extra $200 to the total price. - A calculated "Total" field - A "Submit" button that will send the results to Worldpay No styling of the form is necessary. Please let me know if you have any questions.