Everyone who walked into a Sprint store with an HTC EVO 4G and walked out with an HTC EVO 3D knows that the carrier will buy the old phone for $150. And now those who weren't already aware of the trade-in credit and/or who chose to keep the original EVO or sell it elsewhere definitely know about it too.
Sprint is currently emailing recently upgraded customers to let them know that the buyback value of their old devices (in our case, the EVO 4G). The notice also contains a direct link to the buyback program, where you can complete the offer and even print out a prepaid shipping label.
You don't have to return the 8GB microSD card that came with the phone and as long as it powers on, has a valid ESN, and is in reasonably good cosmetic condition, you'll see a $150 credit on your account within three billing cycles.
Will a rooted EVO that usuallly gets stuck in a boot loop and sometimes horrifies me with a Qualcomm hardware error code (five vibrates followed by blinking green light) be accepted? I guess I'll find out in three months.