A.K.
S.,
Target has a great line of maternity clothes (Liz Lange). Different Targets carry different items, so I would suggest checking in with the maternity department whenever you visit a different Target, just to see what they have. Old Navy also has a great maternity section, and again, the items change, so check in with different Old Navys as well. Motherhood Maternity is pretty darn expensive, but they do have pretty cute stuff. Also, your November due date is not that far off from your Sept - the only difference in clothes is that you might need a few more large sweaters (and maybe a jacket) toward the end. Wait until then to buy those things - you never know how big you're gonna get!!
Good luck,
Amy K