How much you have to donate, and what you get in return depends on which version Tamagotchi you have.
For V3, the donation levels are 5000, 12000, and 30000 points. (These are totals.) At each of these donation levels, you will be given a password. (Note, you have to make at least three donations between each level - meaning if you donate the first 5000 all at once you won't get a password, but if you donate 2000 + 2000 + 1000 you will get a password.) Have a paper and pencil handy, because the password doesn't stay on the screen for long. After you have a password, visit the king in the V3 TamaTown. When you use the 5000-point donation password to visit the king, he will give you a password for the Ring souvenir. When you use the 12000-point donation password to visit the king, he will give you a password for the Cape souvenir. When you use the 30000-point donation password to visit the king, he will give you a password for the Crown souvenir.
For V4, the donation levels are 20000, 70000, and 200000 points. (These are totals.) At each of these donation levels, you will see a message on your Tamagotchi screen telling you to go visit TamaTown. Visit the king in the V4 TamaTown and he will give you a souvenir. The three souvenirs are Scepter, Sword, and Shield. It is not necessary to visit TamaTown immediately after reaching each donation level. You can donate all the way up to the 200000 point level before even once going to visit the king, and still get all three souvenirs. You will just have to visit him three times.
