Check out eBay's Daily Deal on Guitar Hero III: Legends of Rock Bundle for PS3. The MSRP price is normally $69.99, today eBay is offering if via a Daily Deal for $29.99 with free shipping. Here is a link to take you directly to the Guitar Hero III Daily Deal.
If auctions/bidding are more your style, here's a link to Guitar Hero III Auctions currently on eBay.
Below is a Guitar Hero III trailer: