OsCommerce Mod

I hope this makes sense :) In an oscommerce site on the [login to view URL] page you have 9 items listed. They are the newest ones you have added. I have a site that will sell software for PDA's and cell phones but alot of the items are also demo's or freeware. I want the ability that when i add a product, if i make the price of it $0.00 that oscommerce will automatically add a button underneath the product name / description. This will mean that there must be some modification to the admin side as well that will add a field for this information when adding a new product. I have chosen the 20-100 range for the project on here but that is negotiable so send me a pm if your bid is higher and the reasons why it is please. Also before payment is made i will expect to see a working demo on your server with the ability for me to add a product from the admin side to make sure it is what i wanted.