AT&T offers all refurbished iPhones on sale for Black Friday only. Find the iPhones under the "Buy Refurbished" section on the bottom left side.
iPhone 4 32G Refurb - Sale: $199 (normally $249)
iPhone 4 16G Refurb - Sale: $99 (normally $149)
iPhone 3GS 8G Refurb - Sale: $49 (normally $79)