Well I'm downloading space invaders and all 3 DLC pieces since I got a Wii points card that was on sale for 15 dollars I'll let you guys know how it is. The total for all the pieces is around 670 blocks.
From what I'm looking at the download screen each download pack gives you 2 stages and unlocks a ship.
The Game file is 307 Blocks and all 3 DLC neatly fit into 1 file that weighs in a 367 .