You’ve just upgraded your phone, your laptop, or tablet — so what do you do with the old one? There are some easy ways to skip the landfill and turn your trash into treasure. The real question: where can you get the most money for your old gear?

In-Store Trade-In

Retailers want you to walk in the door, so many will pay for your old devices. As of the publish date for this story, an iPhone 3GS will net you $45 in store credit at Radio Shack, $50 at Target, and $70 at Best Buy.

Mail-in Recyclers

Skip the brick-and-mortar hassle by mailing your goods directly to gadget recyclers. Simply go online and get an estimate. You enter make, model, and condition, and they give you a price. If you like the deal offered, you can print out an address label — postage prepaid — and send the gadget in.

For an iPhone 3GS in good condition Gazelle will give you $27; CExChange will give you $44; and NextWorth $67. Note: all these prices fluctuate according to ever-shifting supply and demand, so it’s worth shopping around on the day you’re ready to sell.

Online Sales

You probably know the big players here: Craigslist and eBay. Craigslist works fine if you like the idea of selling locally, but be aware that local prices vary dramatically. For example, in Kansas, I saw iPhone 3GS models listed for around $60 but the same phone was averaging closer to $150 on the San Francisco Craigslist. Of course, these are just the list prices; on Craigslist, there’s no way to know what they actually sold for. And the biggest downside of Craigslist is that you usually have to field dozens of inquiries and then arrange for a handoff.