Xbox 360 Pro + Halo 3 @ Mwave $659
The price on individual components is: Pro Pack $579 up. Halo 3 $90.
Shipping would cost you in the region $10 upwards depending on location and merchant - so all in all you end up about $30 - $40 ahead of what you'd otherwise be paying for the same bundle bought individually or elsewhere.
Only thing - its a limited time deal so if your serious about it you might want to be quick.