Motherhood must be different (meaning better) in the States than in Canada, because it's terrible here!
Not sure if you have Thyme Maternity in the states... but I love those stores!

Old Navy is a good place to try too.  They have some good maternity stuff, but you can also get away with buying some larger regular clothes... at least that's what I have done.

I agree with Aldergray- buy some good basics early and start wearing them.  I switched to maternity pants at like 8 weeks and was so much more comfortable and you'll feel better about yourslef as you body changed.  I've borrowed clothes from my sister and one of my cousins and bought a few things.  I'm about to buy my third round (sigh) b/c it's getting cold out and I have like two pairs of pants that fit. 

I've found that Motherhood (kohl's and BRU- carry a line from motherhood) fits the best.  I sit a lot at work and the secret fit full pannel pants are very comfy.  Everything that I have from both seem to hold up well with frequent wearing and washing.  I have a few pieces from Old Navy and have found that their stuff is hit or miss- sizing and fit being the two biggest factors. 

I've also watched craig's list, garage sales, and resale shops to find some deals.  I bought some regular cardigans and stuff like that so I can wear those things after. 

Kat- must be- Motherhood here is great.  Sometimes the stores get picked over, but I've had great luck with them.

I just had to throw in Target. They have a small line of maternity clothes but they are well priced and great for casual wear and dresses!

I got my jeans and work pants at Gap, some stuff at the Motherhood Maternity outlet, and the vast majority of stuff from Old Navy. I didn't want to spend a ton of money on clothes I wasn't going to wear forever. My personal preference were lots of dresses and maternity leggings. So comfy! Hopefully when I get pregnant again, I'm due around them same time so my maternity clothes will be seasonally appropriate. 

There is a Destination Maternity near me.  It has Pea In The Pod in the front and Motherhood Maternity in the back of the store.  I love both brands, but PITP is way too expensive for me unless they are having killer deals.  I just got a MM dress for $15 at their end of summer sale!!

I also like Khol's & Old Navy for the basics.  And you might be able to find tops and pants for $7 each at Burlington Coat Factory, although I caution you that the quality is less than stellar.

Like everyone else said... the Secret Fit jeans from MM are soo comfy!

I liked the gap maternity jeans. Hated the Bella band.

Looks like I will be heading to my local macys that has a motherhood in it. Thanks for the help ladies!

I liked old navy because their sizes run bigger...just bought regular tops that were loose fitting or designed for looser fit and wore stretchy skirts. Did dresses too. That said, was at H&M today and they seem to carry decent maternity stuff along with what the others have suggested.

I got my maternity clothes from Motherhood, Jcpenneys,  Goodwill, Burke's Outlet, and from my MIL's women group clothing donations.