3.0 figures can't be used in the 2.0 game but the 1.0 and 2.0 figures can be used in the later games (i.e 3.0).
2.0 is marvel
3.0 is star wars.
If I was doing it I would buy the 2.0 starter pack plus a couple of marvel playsets (like different levels) and then the 3.0 game only (you don't need the portal thingy again) plus couple of playsets. All the 2.0 stuff is reduced now.
Thank you attic, I'm really confused by it all, but your advice of going for the 2.0 is a helpful start. I think you're right - I'll her the 2.0 starter pack and the a couple of girly figures. Sounds perfect.
If anyone has found good prices for the XBox 360 starter pack, I would appreciate hearing about them. Thank you x