When making a baby registry, items like bedding, clothes, and diapers for the baby are usually top priority, but there are items do you need to buy before your baby arrives to be prepared for breastfeeding, too. Buy some of these products before you have your baby so you don't need to go to a store in the first few weeks.
Regular bras aren't going to work for breastfeeding, and by the second trimester you probably need to buy new bras anyway, since you are busting out of your old ones. Be open to wearing new bra styles for nursing, since many popular non-nursing bra styles (such as molded-cup bras) don't work well for nursing. Non-wire bras are recommended because an underwire bra that does not fit correctly it can pinch the milk ducts. Most nursing bras are soft-cup and suitable for the changing sizes of your breasts throughout the days and weeks. But don't think you are going to be stuck with frumpy bras until you stop breastfeeding. Linda the Bra Lady has a large selection of nursing bras in every style from soft and practical to uber-sexy.
Nursing tank-tops are so versatile. You can wear them while pregnant and after. Many women live in them for the first few weeks post-partum. Be sure to put one in your birth bag for using during the first 24 hours. They are so comfortable and can be worn under other clothing in place of a bra, and they are also great to sleep in. Try on a few different brands and styles, and buy one of a few different styles to try them out. Once you start breastfeeding, buy more of your favorite style.
"What? I need pads for my breasts?" Yes, you will! You won't need them in the first 2 days post-partum, but once your milk increases in volume (comes in) around day 3, you will need them big time. They are essential while nursing because milk let-down tends to affect both sides, so many women have leakage from the breast that the baby is not nursing on. Also, occasionally, an accidental milk-let down can happen between feedings. Be sure to never leave home without breast pads! Read my blog post about my adventures in the fitting room. Some women continue to need nursing pads as long as they are breastfeeding, but some women can stop using them when their milk volume decreases as their baby gets older and nurses less.
Breast pads come in disposable and washable options, and the washable ones come in a variety of fabrics. Consider the washable variety for every-day use because they can be thrown in with your regular laundry and don't contain any plastic. Plastic-backed pads trap moisture against your skin and can contribute to Thrush. Avent makes a biodegradable, disposable breast pads that contain no plastic. You probably want to have both disposable and washable on hand. I use disposables when I travel, when I wear certain outfits, and when I haven't done the laundry.
Your nipples will be tender the first few weeks of breastfeeding and an early improper latch can even cause small sores on your nipples. Putting lanolin on your nipples after nursing can help heal raw or damaged skin. It is a completely natural product made from wool. It's consistency is much like a super thick petroleum jelly, but it is safe for your baby to eat. If you or your baby have an allergy to wool, talk to a lactation consultant about an alternative product.
Do you really need to buy a pump before your baby is born? Maybe. The only reason you would need to pump your milk during the first few weeks post partum is if you are having trouble breastfeeding. If that happens, you should rent a hospital-grade pump, not use a consumer-grade pump, in order to preserve your milk supply while you work on getting the issues worked out. Also, be sure to ask for a Board Certified Lactation Consultant to help you supplement at breast or have the nurses spoon or cup feed your baby, instead of giving your baby a bottle. This will prevent further issues.
If you are going back to work very quickly, you should consider buying a good (i.e. expensive) double-pump so you can start building reserves in the freezer after a few weeks. It's not necessary to start pumping right away, though. Allow yourself to enjoy your new baby for a while. Also, you don't need to pack the whole freezer with milk before your first day. You really only need to have a supply for about 2 days at first. You will be pumping at work, so you will be replenishing the supply every day. Then, milk can just be put in the fridge because it will be used in the next few days.
If you are not going back to work quickly (or at all) then you can probably wait to buy a pump. You will need one eventually if you ever want to go anywhere without your baby in tow, but you won't be needing one in the first few weeks. It is not recommended to give a bottle to a breastfeeding baby under 4 weeks due to the risk of baby preferring the bottle over the real thing.
I recommend buying a single hand-powered pump, in addition to a double electric pump. I had a big over-supply problem and it would have been great to have a hand pump for those times when I was feeling too full and needed to let off some pressure without expressing too much.