Walmart appears to be dropping the prices on its iPhone 4 and 4S devices, but the deal isn’t available everywhere, at least not yet. Cult of Mac is reporting that prices for AT&T upgrades and new activations have been lowered by $54 and $74 respectively in Edmond, Oklahoma — to $34 for an 8GB iPhone 4 and $114 for a 16GB iPhone 4S. However, of the six stores we contacted around the US, only one in Austin, Texas was offering the 4S for $114, and none had marked down the iPhone 4 below $88. Walmart's site still lists the iPhone 4 at $117 ($29 more expensive than in-store), and notes that "store pricing may vary" for the 4S. It could just be a slow rollout, though. Walmart had a similar price drop last June in advance of the iPhone 4S release, so the move would make sense given the possible summer announcement of Apple’s next mobile device.