847 Kyber Bricks will be required for all class upgrades. The fastest way to obtain this is to focus only spending Kyber Bricks on the individual character class upgrades as the Core Upgrades do not count towards this achievement, however the game does force the spending of 1KB on the Speedy Sprint CU.
180 KBs can be obtained by earning True Jedi on story mission levels.
45 KBs can be obtained by collecting all Mini-Kits.
45 KBs can be obtained by completing all Story Level Challenges.
90 KBs can be obtained by destroying all Kyber Comets.
34 KBs can be obtained by completing all Galaxy Challenges.
FYI 316 KBs are required for all Core Upgrades.
There are 1166 Kyber Bricks in the game. When everything (including the core upgrades) is at 100%, you should still have 3 Kyber Bricks left over.