A field is provided in the link structure for you to add a unique identifier to each URL i.e. 07-06-2013-Balaerics.
LivePricer logs all requests made via its image links and stores the identifier against them as well as the time and date. The LivePricer tools include a reporting function to allow you to specify a date range, and export all requests made in a CSV file. You can then open this in Excel and sort the data by request ID to pull out the relevant prices.