T3 Magazine/Getty Images A refurbished or certified pre-owned Android phone is a safer bet than used because it'll often come with a warranty. You can save money when buying a used Android phone, but proceed with caution – here are seven tips. There was a time when many people upgraded their phones more or less annually to keep up with the newest features, but now that many flagship Android phones cost $1,000 or more, that's no longer practical. When it's time to replace your aging handset, you don't need to buy a new phone at retail; often, a used phone is...