Bargain alert: 16GB iPhone 4 on sale at Walmart for $147That’s $52 off the standard retail price for the 16GB version of the iPhone 4, and the offer is good through June 30. But there are a couple of catches: you’ll only find the Walmart deal in stores, not online (you should call ahead to make sure your local Walmart has the iPhone in stock), and yes—you’ll have to sign a two-year contract with either AT&T or Verizon Wireless.