Don't spend nickel.

https://www.faa.gov/regulations_poli...t_handbook.pdf

https://www.faa.gov/regulations_poli...g_handbook.pdf

https://www.faa.gov/regulations_poli...-H-8083-9A.pdf

https://www.faa.gov/regulations_poli.../00-80T-80.pdf



For what it's worth, the FAA does a great job with pubs. I would hit steep turns hard. They exercise a lot of aerodynamic theory in the oral and touch a lot of skills on the practical.

Good luck. Flight instructing is fun!