Save money or create something unique by making your own cat scratching pad or post by cutting up cardboard boxes. Making a scratching pad usually involves packing strips of cardboard sideways into a box (the box can itself be cardboard or something else like wood). A cardboard scratching post typically stacks cardboard squares over a thin post attached to a base. All you'll generally need is a box cutter and maybe some glue (a glue gun and glue sticks would be ideal or just some non-toxic glue like Elmer's).
Below are some videos to give you ideas to try for yourself.
A cardboard scratcher using any box (even a heart shaped one).
A cardboard cat scratcher using a store display container.
A cardboard cat scratcher you can hang from a doorknob and reverse when it gets worn.
A cardboard cat scratcher the size of a pizza box because it's made from a pizza box.
A cardboard cat-shaped cat scratcher.
A large round cardboard scratcher made from rolled up cardboard strips.
A cardboard scratcher similar to a traditional upright scratching post.
Another upright cardboard scratching post.
An upright cardboard scratching post but with different widths.