A maternity wardrobe needs to dress you through different seasons and accommodate a body that can change size on a daily basis. You'll be reinventing many of these maternity pieces as the staples of your post-partum wardrobe too, so they are sure to get a lot of mileage. Be sure to use your favorite accessories, like scarves, to add your own personality to these classic pieces. To save money, it's wise to buy a few pieces at a time for your current size. Also, don't forget to shop at non-maternity stores for reasonably priced pieces that will work both as your body grows and as it returns back to your pre-preganancy shape.
Start with the basics and expand your wardrobe from the inside out. Maternity underwear used to be classic granny panties. Now, most woman stick with their favorite lingerie brands and just buy a larger size. As your body expands you'll want extra stretchy bras and really soft underwear that are super comfortable to wear as your body grows. To get the most out of your investment, purchase nursing bras to support your new size during pregnancy and you'll be able to wear them while you breastfeed your baby. (Motherhood Maternity, $20)