That is insanity pricing compared to what you get out of the packs. Even though I spend cash here, I have to say no way would I spend any $ in this manner.
Couple this with XP potions being completely useless for me (and end gamers). It's not like more class levels (or more classes) have been added.

Surprised that these boosters are not crafted with gear decons (forged radiant souls)...
Two birds with one stone. Make something useless, useful again. Grind loads of gear to boost your gems.
Hundreds required X 16 classes means I can't see the end.