My 2 year old toddler boy goes through 5 diapers per day. He wears Pampers Cruisers and they're very absorbent.
If you use less absorbent cheaper diapers then your toddler might go through more diapers per day.
I spend around $2.50 per day diapering my 2 year old boy.
The amount I spend on diapers per month for my 2 year old is $75.00 per month.