I'm using a php script for a web site where visitors to the site can keyword search to find specific files. I'd like the vistors to pay for files before they can view them. So, I'm looking for a solution that can see the number searched multiply that by a set dollar amount, send the vistitor to pay that amount via Paypal, and return the visitor to a protected page to view the document in a unique session. Which shopping cart solution would fit this application?
I think you will need a customized shopping cart developed or need to add some addon to the carts like zencart, oscommece, etc.