136983 Need IP of my ebay viewers

I need a way to get the IP of the people who view my Ebay auction, or store a cookie on there computer, or some other way to uniquely identify them. What I want to do is offer a bonus for people who use the "Buy it now" the first time they view my auction, so I need a way to see if they really bought the first time they viewed it and didnt come back 5 days later and bought it. Breifly describe if this is possible and what language you will use to write the script in. Please only bid if I may reuse and resell the code you provide with no royalties other than your bid for this project.