Here:
http://www.reddit.com/r/iPhone/comments/ldmnp/heads_up_walmart_carries_16gb_iphone_4s_for_188/
Also here:
http://www.mainstreet.com/article/smart-spending/technology/iphone-4s-where-you-can-buy-it
And here:
http://www.walmart.com/ip/apple-iphone-4s-16GB-Black-or-White-AT-T-or-Verizon-Price-based-on-new-line-activation-or-eligible-upgrade-with-2-year-contract/13082132#BVSecondaryCustomerRatings
http://www.reddit.com/r/iPhone/comments/ldmnp/heads_up_walmart_carries_16gb_iphone_4s_for_188/
Also here:
http://www.mainstreet.com/article/smart-spending/technology/iphone-4s-where-you-can-buy-it
And here:
http://www.walmart.com/ip/apple-iphone-4s-16GB-Black-or-White-AT-T-or-Verizon-Price-based-on-new-line-activation-or-eligible-upgrade-with-2-year-contract/13082132#BVSecondaryCustomerRatings