If you're in the market for a discounted iPhone 4S on AT&T here's your chance to get one. But you have move fast. Today only, Radio Shack is offering the 16GB iPhone 4S (in black and white) for $149.99 when you sign a new contract. Sadly though, Verizon and Sprint customers are left out of this deal, as are 32GB and 64GB models on AT&T.