Too many times, a family doesn't total the real cost of owning a dog. Many dogs end up in shelters because of medical or obedience problems resulting from the family not factoring these costs into the monthly budget.
Some vets prefer to give four sets.
Feeding a good quality kibble is less expensive in the long run. The dogs tend to eat less and have less health problems. Add more for more Newfs. This one is hard to calculate because the cost vary for different treatments. DO be aware of the possibility and plan accordingly.