When I was pregnant, one place I never went to was the maternity store. As much as I would've loved to wear some nice maternity wear, I just didn't have the funds. And in general, I didn't understand why people spend hundreds of dollars on something they would only wear for about 6 months. So what did I wear?
I already had a pair of black leggings and they ended up being my absolute favorite item to have. I'm talking about the very soft, very stretchy type of leggings, not the cotton ones. I wore them the whole pregnancy and afterwards (and still wear the same pair!). They are super comfy, not tight and I kept them just under the belly.
I also bought a pair of soft/stretchy yoga type pants for a more professional look. I worked until 37 weeks and needed to wear something comfortable.
I found that most of my sweaters were long enough to cover my whole stomach and wore them for as long as I could. I bought 2 long sweater type dresses for about $10 each and wore them with leggings. In the summer, I wore baggy t-shirts I already had in my closet and they also covered the belly.
A friend let me borrow her over-sized jacket for winter and a couple of baggy sweater dresses she no longer needed.
Basically, I did not buy ANY special maternity-wear. The only things I did buy were 3 nursing bras and I wish I had more of those. While still pregnant I also bought a large cotton bra since my breasts grew dramatically! And my friends with larger breasts (lucky gals) also donated a couple of their bras.
If you are looking to save some money on your pregnancy. This is definitely a place to start. Hit the cheap stores and don't be shy to ask your friends if they have anything baggy. I only spent about $60 on my whole pregnancy-wear!