Buy now button with price added

My website [login to view URL] has virtuemart added. The products need a Buy now button on each of them added. In the backend I want to be able to link the buy now button to any URL of my choice for each and every product. By default I want it switched off unless a URL is added to the URL area (which connected to the buy now button). If a URL is entered the price will also need to show on the product (the price set in virtuemart). I have had this done over at [login to view URL] but the developer is now unavailable for work.