J.S.
I got a lot of my clothes on Ebay. The only issue is you have to have some idea what you like, how it fits etc. What I did was find brands of stuff I likes and then bought more pieces on Ebay. I had a hard time find work clothes in any store that were reasonably priced. Target has some (some targets have more than others). I got a lot of good GAP stuff but all on Ebay as no store near me had a maternity section. I had a few essential pieces to mix & match for work :
Black gap skirt
three pair pants (on gap, one liz lange for target and one motherhood maternity)
black blazer that matched all three
and a couple of more casual things for days I didn't have to be as dressy - stretch pants and tunics, stretchy skirts. That matte jersey material is perfect for the expanding belly. I bought a couple of items that were regular sized, just XL, if they had that baby doll cut compatible with a belly and pinned them under my arms, letting them out as needed.
Good luck and congrats!