For the big items, Target tends to put a lot of big stuff on clearance. I got my Eddie Bauer car seat/booster seat combo (it's front facing, but i'm just emphasizing my point) marked down from $99 and I paid something like $30 for it, and it went from being my daughters 5 point system to her booster seat, and it will be the last one she ever has, and I got it at a great bargain. You just have to walk around looking for thier little red clearance stickers. I also got my Jeep brand stroller at Toys R Us. It was the display model and I got it for a fraction of the cost. Sometimes stores will sell their display models, so it's worth a shot to ask!
I'm not sure if you needed a crib or not, but I got my crib at Walmart. It was called something like a 'dutchess' and it was $149, but it requires NO tools to assemble. It just snaps in place, and it was so simple I could put it together by myself when I was pregnant [I tended to move stuff around a lot in anticipation of the little one:)]. It was just as safe as the ones that took an hour to assemble, plus it was beautiful. I tried to find it on the WM website, but it wasn't on there. But they still have it at all the walmarts around my area. Also, make sure you buy some sort of cover for the mattress so if there are leaks or spit ups that go thru the sheet, you can just toss it in the washer and not worry about the mattress.
I agree with another poster that gerber onsies ran way small, and I believe that they shrunk easily. The target brand ones came in a much larger pack (5 or 7 compared to gerbers 3) and were around the same price, and held up just as well. I don't know where you live, but the outlet mall on I-4 (the one where Dollywood is in front of it) has a Carters outlet that has adorable stuff all cheaper than at a dept store.
Buy tons of receiving blankets, and at least a pack or two of cloth diapers, for wiping and throwing over your sholder. Cheaper than burp clothes, work just as well, and come around 12 to a pack.
As far as a changing table went, I just used the little folding pad that usually comes with your diaper bag, or a receiving blanket and plopped her on the floor to change her. I didn't see spending a hundred bucks on a changing table. But, it's a matter of taste because i had friends who swore by them. They just were not worth the money to me.
Diapers: I used all the expensive diapers that I got for my baby showers, then I started using the less expensive ones. Luvs worked really well for me. If you have a sams card, they sell HUGE boxes of diapers at very reasonable prices. And also, HUGE boxes of good, sturdy wipes for about $12 a box. And you can never have enough wipes.
I didn't breastfeed, so I can't help you with that one. Except buy lots of bottles for your pumping. Tons. Also, buy the clear nipples for them, and not the yellowish ones. They have a funny taste because of what they are made of, while the clear ones have no taste.
AND: My BIGGEST piece of advice for ANY NEW MOM: Register. Go online, and go to Pampers.com, and Enfamil.com, and Huggies.com, and gerber.com. Any brand name that you can think of that concerns babies, go to their website and SIGN UP. They send you free samples, and great coupons, and there is no charge for any of them. Enfamil asked what kind of formula I used and send me an ENTIRE $20 CAN OF IT FREE. They then send me coupon after coupon for formula. And they were GOOD coupons. They started out being $12 off a can of formula, $10 of a can, $8 off a can. In months the amounts go down, but they start out really high. And then for the first year after you quit getting the big coupons they send you $1.00 off and $0.50 off coupons. So you still get something. Pampers and Huggies and Luvs will sent you $5 or $6 off coupons, and free samples. I still get them now and my daughter has been out of diapers for years. Gerber sends you coupons off clothes and pacifiers and soap. It's a great idea, and it only takes a few minutes to sign up. Also, join Publix's baby club. They send great coupons too.
My daughter is four, so that's all I can remember right now. :)
Oh, and congrats :)