I need a programmer who has experience with the banner management software RevSense (product web site and demo here: [url removed, login to view]). I need to modify the software to bill for banner ads on a monthly basis through PayPal. Software currently bills a set minimum $ figure. Need it to calculate billing amount based on daily ad rate for a particular ad zone x 30 days. Software supports PayPal IPN, but only single payments. Need to modify it to handle recurring subscription payments. Please let me know what information or code samples you need to accurately bid on this project. The full script is already installed and functional.