What iron supplement should I take? No iron in prenatal.

The lowest iron amount at most of the stores I've been to had 67mg of iron in it and was to be taken once a day. 67mg sounds like quite a lot, and I realized I'm not really sure the extra amount that a pregnant women should be getting in their prenatals. My prenatals have no iron in it but they are the only ones I can keep down. Suggestions?