Best of the Best style Soccer Spot the Ball Grid Software

I currently require a web based application that allows me to enter a "spot the ball" competition on my website. This needs to be a grid very similar to that of the way that [login to view URL] operate their online supercar competition where by the customer needs to identify where they believe a soccer ball has been removed from a picture in order to win the competition. The grid needs to be incredibly fine as I need to sell around 100,000 tickets per competition. i.e. the grid would need to a large number of coordinates available for people to choose from. To gain a better understanding of what I am trying to explain, please visit [login to view URL] and click on "buy tickets" to take you to the competition. Here you'll see the same type of page that I am trying to add to my site. When customers choose the grid, they also need the option of making multiple selections (guesses) and each time they make a guess it will need to be linked to a payment shopping cart. So that when they are finished making their selection, and proceed to payment, I need to be able to relate the coordinates to each seperate transaction. It may be the case that this project may also need a members area for this to be possible, or which I will need to add the development of this to project. At present I intend on using Paypal as the payment processor, however this may change depending on legal issues with them. Ideally I'd like to see examples of similar projects before awarding the project.