Thanks! It is kinda hard to say exactly. I spent $6.50 on the twine for the scratching post. I used it all but I might add some more, I am not sure.
All the other wood came from Home Depot reject wood pile. Some were scrapes from my old projects. The 4x4 was $2, and back was $4, and then I got the carpet from a local carpet store as a scrap piece. They were asking $10 for it but I talked them down to $7. And about $6 for the carpet glue plus I used some staples I had.
So I guess about about $26-$30.