Are you an iPhone 4S owner? Looking to swap up for the next new phone? Bryan Wolfe over at App Advice writes about Apple's iPhone trade-in options.
Fulfilled through its PowerON partner ("Apple is not involved in the transaction between PowerON and the Reuse & Recycling service customers."), the Reuse and Recycling program offers up to $345 for top-of-the-line 4S's in perfect condition.
The site quoted $280 for my middle-range, lightly-used 32 GB 4S, regardless of whether I ship back the power cord or not. That's an estimate, likely an upper bound, which allows PowerON to evaluate the unit upon receipt.
You provide your contact details, agree to the terms and conditions, and affirm that the unit is not stolen. PowerON supplies you with prepaid options for packaging and shipping. After your unit is received and inspected, you'll receive an Apple gift card.
Prices are, of course, subject to change as the demand for your unit changes over time. Wolfe points out that Gazelle, the iOS buyback powerhouse, is offering an iPhone price lock, good until October 1st. You can lock in today's price now, and keep your phone until the new one ships. They're offering $275 for the same 32 GB 4S unit as PowerON, i.e. almost identically valued.
Whatever option you decide on, make sure to wipe your unit before shipping it. Use Settings > General > Reset > Erase All Content and Settings.