The best way to determine the best price for a used iPhone 4S is to compare prices on the Internet from major retailers. Amazon.com, for instance, lists a used 16 gigabyte iPhone 4S for the Verizon network for $80, as of April 2015.
Used iPhone 4S models are also sold on eBay by both private sellers and retailers. Some of these phones are unlocked, which means they can be used on any network, but others are specific to certain networks, such as Verizon.
Another online retailer to look at in order to determine a good price for a used iPhone 4S is Glyde.com. This site sells used iPhone 4S models from about $67 to $259. The site sells iPhone 4S models in both black and white, and sizes range from 8 gigabytes to 64 gigabytes. The phones sold on Glyde.com are for Verizon, AT&T, Sprint and T-Mobile.
When buying a used iPhone 4S from Glyde.com, a buyer has the choice of options based on condition. A phone in good condition is the most inexpensive and is fully functional. However, these phones show signs of wear and may include some noticeable scratches. Excellent condition iPhone 4S models from this website are also fully functional but may have minor cosmetic problems. Glyde.com also sells certified iPhone 4S models that are the most expensive, but have been professionally refurbished.