Anyway, in theory you don't have to replace much of anything besides your goal of the replacing the ball and seals. If all the other parts are in good shape you can reuse them if you have the tools to get them all apart. Some items make sense to replace like the top pin and bushing, perhaps the bottom bearing and inner axle bearing. New hub seal.
As was mentioned, don't get too caught up in replacing everything you touch just because. If money is concern then consider reusing what you already have.
"Clubs are for Chumps" Club president