I’ve updated the Buy This Book WordPress plugin to the latest version, and I’m also planning on making a version that can be used on a free WordPress site – some technical knowledge involved, but better than nothing, I hope.
I’ve made some security fixes and code updates in this version – mostly stuff I should have done on release, but that I didn’t get to for various reasons. You can still use version 1.0, but I recommend updating it obviously.
Please note that the update will remove your links. You’ll need to add them again. Sorry about this, it’s a side effect of the security and modification stuff.