Modification to Simple Paypal Shopping Cart

I need a simple tweak / change to your simple shopping cart script. *Users can create their own store and payments are processed via Paypal. *The change needed: next to the 'buy' button, i need an option (same button style as 'buy') that says 'trade.' When users add products to their store, they select: "buy only" "trade only" or both "buy" AND "trade" - in the site's main search bar (in the header) users can choose to show 'buy' 'trade' or 'both buy & trade' - TO SAVE TIME, YOU ARE FREE TO USE A SHOPPING CART SCRIPT YOU ALREADY HAVE & just make the above modifications. This needs to be a simple / clean shopping cart (all white background) that allows multiple photos of the products, product description, shipping details, & price. Shouldn't take more than 2 hrs for someone who has a simple / clean shopping cart and knows how to program / modify a database. Have a question regarding this project? Please let me know.