I'm buying a Jeppesen Private Pilot textbook. A new copy on amazon is $85 and the print date is January 01, 2018. On the Jeppesen website is $90 but I don't know if the date is more recent. I saw a used copy from 2013 for $35 on another website and wanted to ask if you guys that know more than me if it's ok to buy an older copy or if it's severely outdated.