You can go to GP or Family Planning clinic to get a prescription for Folic Acid ($5 for three months supply)which is what Elevit has, but a lot cheaper because government pays for it. Elevit is expensive only because of the brand+multivitamin which you don't necessary need.
You take Folic Acid before pregnancy and until 12 week preg.
孕期和哺乳期都要吃的 is iodine/Neurokare, and you don't start iodine until actually pregnant.... not folic acid
Folic Acid you take before pregnancy and until 12 week pregnant