You might've heard that Amazon has expanded its trade-in program, and will now pay for used gadgets with gift cards. What you might not know is that Amazon isn't the only retailer who buys back old electronics.

Plenty of other websites offer to pay for your used gadgets, all with different strengths and weaknesses. In March, I compared seven of these sites, along with Best Buy's buyback program, to determine who pays the most for used electronics. Let's compare those findings to Amazon's program to see if it's the best deal for gadget trade-ins.

Apple Product Trade-Ins: Good Deal

In my previous comparison, eBay Instant Sale offered the best trade-in values for used iPhones and iPads, but Amazon is far superior.

Right now, Amazon will pay $185 for a 32 GB iPhone 3GS in "good" condition, compared to $172 with eBay. For a 64 GB first-gen iPad with Wi-Fi, Amazon pays $306.50, compared to $255 through eBay.

Other Phones and Tablets: Mixed Results

Amazon's hearty trade-in values on iPhones and iPads didn't carry over to other phones and tablets.

Two of the phones I compared previously, the Blackberry Bold 9000 and Motorola Droid, are not accepted through Amazon. One of the phones Amazon does accept, the Droid Incredible 2, pays only $121.50 in good condition, compared to $186 through eBay. Amazon does offer a better trade-in value on a used Motorola Xoom Wi-Fi, but it doesn't accept 3G models.

Trade-in values were worse than eBay Instant Sale for the Samsung Galaxy Tab.

No Laptops, Game Consoles, TVs or Blu-ray Players

This made my job really easy. Amazon doesn't electronics in any of the above categories. For laptops, game consoles and Blu-ray players, stick with Gazelle, which had the best trade-in values in my previous comparison.

Gazelle also has a handy trade-in utility for laptops, which spits out a price based on the raw tech specs you enter. For TVs, Radio Shack is the only site that does trade-ins, and its selection is limited.

Don't Bother With Cameras

Amazon accepts cameras for trade-in, but not nearly as many as Gazelle, and often at lower prices. Nikon's Coolpix P100, for instance, fetches $80 in good condition on Amazon, and $128 on Gazelle.

Other Factors

Even if you find a good price for your old gadgets on Amazon, your only payment option is an Amazon gift card. eBay pays through Paypal, and Gazelle pays by check, among other options. Also, Amazon allows you only one week to send in your device with a pre-paid shipping label, whereas Gazelle honors its trade-in values for 30 days.

Amazon has great trade-in values for Apple products, but it desperately needs to expand the range of other electroncs that it accepts for trade-in. And even if that happens, Amazon already has a lot of tough competition.