Not so. It turns out that you can sell textbooks online Amazon even if they were bought elsewhere.
A little more research and I found the search box to see what books they were buying back. Sure enough. They were buying the title that I hoped to sell. Not only that, but they were offering more than the school bookstore.
Selling textbooks online to Amazon was easy. I just clicked around, printed the shipping label and plopped that book in the mail faster than you can say "textbook buyback". Amazon even paid the postage!
All of this happened just over a week ago. The gift certificate amount hit my Amazon account yesterday, so now I'm looking at what all is needed for next semester. One easy decision is already made. I'll be selling my textbooks online next semester without hesitation.
They will also buy some electronics, movies and other items. This is where I found the link and the screenshot of the gift card amount is above.