If you want to staple standard office paper into a booklet, you need a long arm stapler — standard desktop staplers are not long enough to staple the middle of a page. Specialised booklet staplers can cost $40 or more, but with some aluminium rectangular tubing, a hacksaw and a drill you can augment a bargain store stapler and give it much more reach.
Instructables user kenyer disassembled the donor stapler, cut two pieces of aluminium stock to size and formed them into a U-beam, and attached the two pieces of aluminium stock to the stapler using screws at a 90-degree angle. Now the stapler doesn't need to be as long to access the spine of your booklet.
DIY Booklet Stapler [Instructables]