you can revoke them i believe. but my suggestion is to try and find it in a bargain bin.
If you mean finding a used copy in a bargain bin, how would that help? It would still only have the limited activations, and less if he bought it used.
Make a shortcut to the game. Right click on the shortcut and choose properties. In the target line, you'll have something like this:
"G:\Batman Arkham City GOTY\Binaries\Win32\BatmanAC.exe"
Simply add /revoke to the end so it will look like this:
"G:\Batman Arkham City GOTY\Binaries\Win32\BatmanAC.exe" /revoke
Run the shorcut. Now, you've got your activation back.
It also says you can install it on up to 10 pc's. I thought that was kind of odd.