Tips for buying used and unlocked phones
People that I talk to about phones primarily buy through their carrier and many still think they are getting the phone for free or for less than $100. With low-price, no-contract, wireless service providers and even traditional wireless carriers with no-contract options, bringing your own phone is usually the most cost-effective solution.
Most of the phones that I purchase are unlocked or no-contract devices because I like to avoid carrier bloatware and prefer to have full control over my purchases. I also sell quite a few of my phones to offset the cost of new phones that I can test and write about here on ZDNet.
Buying from a private party
The primary options for purchasing a used, refurb, or new smartphone from a private party include eBay, Craigslist, Swappa, social networks, and through a friend.
Swappa: I highly recommend Swappa for gently used and new phones. I've sold 11 devices and purchased four over the last year with only one sale having a minor issue.
One great feature of Swappa is the selling history chart that shows you the selling price for each phone model. Most models drop over time, but every once in a while prices will rise as something changes in the market.
All devices have the ESN checked so you can trust you won't be buying a phone that someone owes on an equipment installation plan or that someone stole from a carrier-managed account holder. They don't allow bad ESNs, cracked screens, water damage, or junk devices. There is actually a boneyard set aside for that, but the main sale site contains high quality devices. There are no seller fees and the buyer just pays a flat $10 fee.
Payments are made through PayPal so they are protected and there is a feedback system that also ties into the eBay feedback system. You can negotiate on the sale page and I've had great success in getting sellers to come down a bit in price. The Swappa staff is also very responsive.
AR + VR
eBay: I've been on eBay since early 1999 and have 100 percent positive feedback. While eBay can be good for hard to find devices and popular devices, prices are usually higher and there are high seller fees.
There are good sellers on eBay, but you may also risk buying phones with issues. If you are going to buy on eBay (that is how I bought my Apple Watch), make sure to check out the seller feedback comments and compare the device price to eBay history. If a deal is too good to be true, it often is.
Craigslist: A few years ago when Windows Mobile was hot, I bought phones on Craigslist since there are a lot of Microsoft people in the Seattle area who apparently had extra devices. Craigslist transactions take time and effort though as you need to meet the seller in person and then also pay in cash.
The device could still have payments due from a carrier, it could be locked to a carrier, and there is no feedback system for you to base any trust in the seller. I now just use Craigslist for household items, such as tools and furniture.
If you are going to use Craigslist for mobile devices, then I highly recommend you meet the seller in a busy public place for your own safety. You should also try to check out the device as closely as possible, but there is still a risk that it could have a bad ESN or still have an outstanding EIP balance. I would contact the seller before you meet and request to have a photo of the ESN or IMEI sent so you can check with the carrier to see if it is stolen or still has outstanding payments.
Social networks and friends: Before I post to Swappa, I will often post a note on Twitter or Facebook to give my followers a chance to buy one of my phones at a discounted price. You must be able to trust the person you are buying from since there is no system for checking the device.
The social network itself can serve as a feedback system though so if someone is selling junk you are likely to find out.
Buying from a retailer
You can also buy refurbished or no-contract phones through your wireless carrier, manufacturer, or other online retailer. Refurbished phones are typically in great shape and most come with some kind of warranty as well. You generally won't find a warranty when buying through a private party, so if you tend to have issues with your phones then you may want to consider a retailer.
I purchased my last couple of BlackBerry smartphones and Apple iPhones directly from BlackBerry and Apple stores. These were unlocked, no-contract phones with full warranties and good return policies.
Gazelle: You may recognize Gazelle as a great place to sell your use iPhone or iPad, but I also just learned it launched a retail site where you can buy certified used devices. If you want to buy phones with that undergo a 30-point inspection (including lost or stolen verification) and come with a 30-day return policy then you might want to check out Gazelle.
Gazelle offers used iPhones ($s and up), Galaxy S (version III, 4, and 5) models, and Apple iPads (version 2 and up) to choose from. Prices seem pretty reasonable and the peace of mind with the return policy may have value for some buyers.
Some of my favorite online retailers for these phones include Amazon, Newegg, B&H Photo and Video, and Handtec in the UK. You will usually pay a premium price for the latest and greatest smartphones from one of these online retailers, but if you are an early adopter and need to have it now then these are valid places to consider. Feel free to share your favorite online retailer in the comments too.
Amazon is a massive retailer and I find that it requires me to spend lots of time filtering to find just what I want. Make sure you check carrier compatibility before jumping on the first search result. T-Mobile data service is not fully supported on all international phones so do your research if you are with T-Mobile or an affiliate.
I do recommend that you clearly read the return and warranty policies for each online retailer you are considering. Some policies are not very good and I've found it easier to just list the phone up on Swappa instead of trying to return to the store I bought it from.