Thanks. As I mentioned, the site is still under construction so the following page needs a lot of updating. What we need is: when the customer clicks on "add to cart" and gets the Paypal page, they can then fill in a box with a discount/reference number to qualify for a discounted price. Ideally at this stage we would also like to add an "opt out" button if they don't want to receive information from 3rd parties.
http://www.emigratetv.com/shop.html

Any help/advice would be much appreciated.