Tunics as maternity tops?

My husband and I are hoping to be starting our family in the next few months and I've been looking into the logistics of pregnancy and it's expensive! We are poor college kids and having to buy overpriced maternity clothes is daunting. I work in a clothing warehouse, and I'm beginning to think that I could make a large tunic work. And it's something that I can wear when I'm not pregnant. Thoughts?