Sprint offers the Apple iPhone 4S 16GB now on sale for FREE with free shipping for new customers who port their number to a new line of service.  Available in either black or white.  This is the best total savings we've seen currently directly from any carrier.

Note that the 8GB model is FREE as well for all customers, and does not require the "bring your number" savings.

The Sprint Apple iPhone 4S features a dual-core A5 processor (same as iPad 2) with advanced graphics, iOS 5, Retina display, an advanced 8MP camera (records in 1080p), CDMA compatibility, Siri Voice Recognition, 8 hours of 3G talk time, and more.