MobilePros1 via eBay offers the refurbished Unlocked Apple iPhone 4S 16GB GSM Smartphone in Black for $127.77 with free shipping. That's $22 under our mention of a refurb from last winter and the best deal we've seen for a refurbished Apple iPhone 4s 16GB model. (It's also a current low for a refurb by $32.) It's compatible with GSM networks such as AT&T, T-Mobile, and Vodafone; it can't be used with CDMA networks such as Verizon or Sprint.
Note: No warranty information is provided.