Selling Online: Amazon.com and Half.com
When I was in college, I joined Half.com, using it to buy my textbooks more cheaply and sell them for more than I'd get if I relied exclusively on the UGA bookstore or the off-campus bookstores in Athens. This was largely a success, even with fairly obscure books like At Thy Call We Did Not Falter and 32 Battalion, which I used for my senior thesis on the end of apartheid and the role played by the Battle of Cuito Cuanavale.
Since then, I've bought and sold a few items here and there. Among other things, I've learned the lesson that if you want to keep more of the money Half.com gives you for shipping, ship as cheaply as possible. For small books, it's better to take a big manila envelope and pack the book into it with a lot of plastic grocery bags for cushioning rather than buy an expensive mailer from the Post Office. I actually lost money on shipping on my most recent transaction because of that.
I recently tried to post the BattleTech source-book Jihad Secrets: The Blake Documents, which I purchased in order to learn the (possible) fate of Clan Wolverine, a renegade Clan that was supposedly exterminated by the other Clans but in all likelihood managed to escape back to the Inner Sphere. Although I'm interested once more in writing BattleTech fiction, I'm not interested in the Word of Blake Jihad or the FedCom Civil War, so I figured it'd be better to make some money selling the book to someone who'd appreciate it more than letting it gather dust.
However, for some reason Half.com would not accept the ISBN number. Rather than let that get me down, I decided to post it for sale on Amazon.com.
Here is my seller page on Amazon. So far it's just Jihad Secrets that's available, but I might post other items that have been sitting on Half.com forever without selling. If you're interested in the Word of Blake Jihad and Clan Wolverine, I'd recommend buying it.