Free is the best price. I will try to point you to free items that will help learn about relevant, current topics as often as I find them.
The Princeton Bitcoin Book by Arvind Narayanan, Joseph Bonneau, Edward Felten, Andrew Miller and Steven Goldfeder is a free download — it’s over 300 pages and is intended for people “looking to truly understand how Bitcoin works at a technical level and have a basic familiarity with computer science and programming.”
dudgirl press 