Consumer Reports' ShopSmart magazine has some advice on how to do it.
In ShopSmart's search, a Samsung Galaxy S2 fetched $94 and an Apple iPad 2 went for $190.
ShopSmart found the website Glyde often quoted the highest prices.
Meanwhile, Amazon proved best for random gadgets, like hard drives and speakers.
And NextWorth allows you to send items in, or drop them off at stores - including Target.
"You really have to check different sites, at different times because we found that prices vary from site to site, and prices can change over time, too," said Lisa Lee Freeman of ShopSmart magazine.
If the price you're offered doesn't seem worth it, consider a donation.
Cristina.org connects you with local organizations that accept old electronics.
Even if your items are not wanted by anyone, you should still recycle them responsibly. Stores such as Staples and Best Buy will take old computers off your hands.
Or, you can drop them off at a local recycling center. At the very least, you can keep more junk out of the landfills.
Whatever you do with your old electronics, be sure to wipe them clean of all your personal data first.
For details on how to do that, visit the Consumer Reports website.