Less than 10 days before moving date: Greek yogurt, oats, milk, etc.

I am looking for some general information about Greek yogurt and milk.

Is it correct that the largest containers are only 1L big? Is there no way to get bigger milk or Greek yogurt?

Where are the best places with decent discount for these?

I am also able to make my own Greek yogurt, is it expensive to buy 4L of milk in Japan? That amount would possibly make me 3.25L of Greek yogurt which would last me more than a week.

If anybody has experience with these please send any information!

Are there Any good alternatives to apples that are cheap? If so where to get them?

Thank you for all the info!