Whats worth buying?

So I have the Stormlight Handbook and love the underlying system but really dont plan on running a game in Roshar, rather adapting the system to my homebrew world. All that said what if the other books are worth buying?

Are the world guide worth buying for enemy statblocks, (I heard thats that book they are in) and are the mistborn books worth buing for other class options and the like?