Gamemasters will need the Savage Worlds ruleset, the Marshall's Handbook (which includes the extension and custom skin) and the Player's Guide. Players can choose to purchase the Player's Guide to improve their experience while playing but they are not required to. Additionally, there are token paks available for Deadlands in the store as well -- from some time ago.
Thanks to PhantomWhale for all his hard work on this and the latest Savage Worlds upgrade.