Even if you eat lot of green leafy vegetables fortified soy milks can be a significant aide in helping you meet your calcium needs.
Out of curiosity I did a price comparison in my local co-op today.
A half gallon of SILK ( a very tasty brand of fortified soy milk ) cost $3.39. One serving ( 1 cup ) has 30% of the RDA for calcium ( about 300 mg ), 50% of the b-12, and vitamin D. One half gallon container has 8 servings. In other words drinking SILK to supplement your calcium costs 42 cents per cup ( 1 serving ).
I found a powdered soymilk at my co-op as well called "Better Than Milk". It cost $9.35 per container which has 32 servings. Each serving has 30% of the RDA for calcium like SILK, as well as 30% of the RDA for b-12. Total cost per serving: 29 cents.