RB2 for Wii supports the download (and storage on SD card) of tracks via the in-game music store only; you'll have to add Wii Points through the Wii Shop Channel, per usual. PS2 owners ... sorry, but your DLC is in another castle.
Here's the package / pricing breakdown. Note that peripherals for the PS2 version are already on sale.
- Special Edition Bundle (Wii) – $189.99
- Standalone Software (Wii) – $49.99
- Standalone Drums (Wii) – $89.99
- Standalone Guitar (Wii) – $69.99
- Standalone Software (PS2) – $49.99