In Super Mario Galaxy 2 for the Wii, Mario has his own personal Banker Toad on the Mario star base where you can deposit star bits, typically so you can use them with other characters. The  other primary benefit though is to unlock the other star in the Grandmaster Galaxy. As you deposit stars, the appearance of the toad will change which is quite amusing as well. Here are the number of star bits you need to deposit in order to unlock the banker’s items:
1. Toad with Glasses – 1000 star bits
2. Toad with Spear and Shield – 2000 star bits
3. Toad with Pickaxe – 4000 star bits
4. Diver Toad – 6000 star bits
5. Explorer Toad – 9000 star bits
6. Grandmaster Galaxy “The Perfect Run” – 9999 star bits