My one bigger (like over $20) maternity purchase was for a denim skirt. I bought it from the gap and practically lived in it throughout my pregnancy. During postpartum time, I still liked to wear it because the wider elastic waistband helped to "hold in" my still jiggly stomach.
http://www.gap.com/browse/product.do...d=1&pid=637340
While the cost is higher, they frequently have 25% off coupon codes, and I got a ton of wear out of this item.
Aside from that purchase, I just wore my stretchier pre-pregnancy skirts throughout my pregnancy. (Granted, I didn't gain a ton of weight and I carried pretty small.) Anyway, I highly recommend Patagonia's Morning Glory skirt. I just wore the waistband under my belly. It did begin to get a little tight toward the end, though. I also have the
Patagonia Kamala skirt and I think it would work well during pregnancy.
I also have this skirt. It worked well for me during pregnancy, but the price is high and the quality is low. (I hate admitting that, because I prefer to support Etsy sellers...)
http://www.etsy.com/listing/56667693...irtdress-local
I fantasized about buying myself one of these skirts during my pregnancy.
http://store.textureclothing.com/comfyskirts.html
I know these ideas are more expensive, BUT they will work well far beyond your pregnancy. Personally, I'd much rather shell out more money for a skirt that will be a favorite for years (like the Patagonia skirts) rather than some of the cheapie maternity things that I bought from Old Navy and will never wear again (except perhaps during a future pregnancy).