I've collected way more than enough egg cracker boosters from doing quests... I'm on lvl 2324 and I've saved up close to 35 of them and I always use them on required boards regardless if I "really" need to or not... The app always seems to crash when my app data gets to large.. So, instead of just hoarding them, I definitely use my boosters.
Granted, I do a lot of quests (823k beans)... But trust me, do the quests. They will give you the boosters needed.