From Kotov, Najdorf himself and Bronstein to Polugaevsky, Fischer, Tal, Gligoric, Portisch, Kasparov, Nunn, Ljubojevic, Timman, these and many others have made serious contributions in this line. Among today’s younger generation Vachier Lagrave and Nepomniachtchi head the many standard-bearers of the Najdorf. It is important also to mention players who contributed with the white pieces: Karpov, Geller, Velimirovic, Anand, Short, and even Fischer himself, who often played the Sozin line. Many others too have been trying to find the ultimate weapon against such a strong line.
Sometimes it is a new positional idea and sometimes a tactical one, depending on players’ styles, but the Najdorf is very resilient and new efforts by one side are countered by new efforts from the other. It just goes from strength to strength.
Milos Pavlovic "The Modernized Najdorf, A Complete Repertoire for Black"
Depend of province in Canada, around 10-20 CAD, during 2-7 days.