The Nokia N-Gage QD is now shipping in the US. It is being bundled with Tony Hawk's Pro Skater and is selling for $99-$199 depending on whether you get a contract or not. At this time the N-Gage QD can only be activated on T-Mobile, but AT&T Wireless is expected to start selling them soon.
At $199 without a contract this is about the cheapest Series 60 mobile phone you can purchase. Despite the price it still has Bluetooth so getting new applications onto the Symbian powered device is a snap.