I bought the One Source Prenatal Vitamins at Walmart one time when I needed prenatal vitamins. They were less expensive than the other brands, but still contained all of the essential vitamins and minerals you need when pregnant, trying to conceive or breastfeeding. Actaully they 50% more calcium than other brands. I have been really happy with this purchase.
These vitamins are smaller than other prenatal vitamins I've tried and this makes them much eaiser to swallow. You do have to take two a day instead of one. I guess that's how they get their smaller size. It's worth it to me though to not have to swallow a big horse pill every day! Another thing about these vitamins that I like is that they have never made me feel nauseous. The last thing you need when you already have morning sickness is a vitamin that makes you feel sick too.
If you are looking for a prenatal vitamin that's not so expensive, One Source Prenatals Vitamins are a great choice.