Never calculated cost, buy pasta in bulk and shred block cheese to reduce overall cost.
2 cups elbow macaroni cooked & drained
2 tbsp flour
1 ½ cups milk.
1 ½ cups shredded cheddar cheese
Dissolve 2 tbsp flour in ½ cup milk set a side. In large pot put in 1 cup milk and heat to hot not boiling over med heat. Add in milk and flour mixture and stir in until it thickens, about 3 minutes. Turn heat off and mix in 1 ½ cups shredded cheddar cheese. When well mixed and cheese is melted add in cooked noodles. Season to taste, little salt and black pepper is good.
Cheese types can be mixed up to taste.