https://www.bleepingcomputer.com/offer/deals/get-98-percent-off-the-complete-microsoft-365-security-training-bundle-deal/

In this deal you get access to 36 courses and over 80 hours of training on Enterprise Mobility and Security, with courses on securing Office 365 and Windows 10 installations. These eBooks normally have a combined value of $2,999.99, but have been discounted 98% to $49.99 as part of this deal.  

This eBook bundle comes with a 15 day satisfaction guarantee. If you're unsatisfied for any reason, just contact Stackcommerce and they will issue a full store credit within 15 days of purchase.