If the main game is 50 dollars, both other games are ´expansion-priced' aka 20-30 dollars. I will be OK with it, they'll just be expansion packs, did you ever complain about Brood War or Frozen Throne? No. maybe because those wern't announced before the game was released, but whatever.

Also Blizzard makes top quality games, they deserve the money. You could've also payed 80 dollars in total for the Command and Conquer 3 + expansion. But I would rather pay 110 dollars for the full Starcraft 2 experience :)