Came here wondering the same thing. Based on Forza 3 special edition, or whatever it was called, I don't see prices dropping too quickly for this title-at least not like how most new releases have been dropping...
Kmart will have a $20 gaming coupon, but it's not sure yet if that will be on launch day. Check the Kmart sticky in the next few days. Expect Amazon to respond with at least $10.