Here's a picture of the Coca Cola 500 day pin we mentioned a couple of days ago.
Seems like there are already a few on eBay. Some have sold for around £25/£30 and others are listed from £25 to £45 at the time of writing. We're trying to find out the issue size for this pin. Interestingly, this one does not have a London 2012 logo on it, but the back markings are consistent with the first pin.