If you use Amazon, you can get a plug-in called:
http://us.camelcamelcamel.com/
It tracks the prices on Amazon overtime. According to it, a used copy sold for $3 on Dec 19, and new by a 3rd part for $9 on Dec 8. You can setup watches to email you when it hits a set price. It is a pretty neat plugin. It is shocking to see how much Amazon moves their prices around to test the market.