I'll chime in with my little bit of advice. We have a 20 month old daughter and plan on getting pregnant again this year. For our first, we tried to be "frugal and minimal" according to normal standards, and I would say that we accomplished being minimal, but not so much frugal. We still didn't spend nearly what some people spend though. Some of what we bought was AWESOME and worth every penny, some was not.
The best quote I ever heard was "babies are not expensive; the lifestyle people want with babies is." Think about the level of lifestyle you are comfortable with for your family and spend accordingly
NEEDS
Diapers. Even if you EC, you won't be able to do it full time. I started another thread about diapering and cloth vs disposables, so look at that if you have questions. Either way can be done economically, just depends on how much work you want to do.
Food. Lots has been said already on breast vs bottle. We breastfed exclusively for 6 months and verrrry slowly introduced solids after that. Now we are verrrry slowly weaning at 20 months. Breastfeeding has been wonderful for us overall, much easier and much cheaper than formula, but it IS a skill that takes time for you and your baby to learn. Keep a couple bottles and all the free formula samples you get on hand just in case.
Clothing. Go simple. Used is great if you can find good prices. For various reasons, we never really got hand me downs. We had the first girl in my husband's family, so maybe that's why. My mother bought us ~70% of the clothing we used for our girl's first year. I bought a bunch of other stuff we absolutely did not need. We're holding onto all that clothing for now in case the next is a girl. I will say that used can be awesome if the price is right. Look for consignment sales and big bags of clothing for sale on CL or at garage sales. Goodwill is often just as expensive as Carter's or Old Navy clearance rack, son new can be very affordable too, as long as you don't go nuts. Cotton sleepers for a summer baby, fleece sleepers for a winter baby. Some onesies and soft pants are essential. Get enough clothing to last for a few days. Also get a few large Muslin swaddling blankets and several burp cloths. Flannel blankets are also nice for colder temps.
Love and enrichment. As has been said, YOU are the best toy. When we do buy toys (not very often), they are quality wood, metal, or rubber. I recommend Hape and Haba brands, both are on Amazon. More than that, children need love and support and attention. You cannot spoil a baby. It simply is impossible. Toddlers, yes. Babies, no.
Car Seat. I do recommend an infant bucket seat. Convertible car seats are made for bigger children and usually do not fit small infants well, leaving them at risk in case of an accident. The notable exception to this is the Combi Coccoro. It is a much smaller seat that will fit a newborn, but the trade off is that it will be outgrown much sooner than other convertibles, often before the age of 2 (all children MUST rear face until age 2, but preferably until age 4). So an infant bucket seat provides a better fit for small babies and does offer great convenience and safety. It's much easier to get that squirmy newborn buckled in inside your house rather than outside in the pouring rain or the blowing wind.
www.csftl.org is the best website for car seat safety, recommendations, and troubleshooting. There are many, many affordable options for infant, convertible, and booster seats. Please take the time to make sure that your babies and children are riding safely.
Wrap/Carrier/Sling. This is a need if you ever hope to do anything with two hands ever again. There are so many styles and so many different kinds of contraptions made to hold an infant or toddler to your body. The soft-structured carrier (e.g. Ergobaby) is the most popular, but far from the only choice. Look up Babywearing International and go to a meeting near you. The leaders are certified and will help you find the right carrier for your family. They usually have a large selection of carriers at meetings to try on. TRY BEFORE YOU BUY.
A place to sleep. Skip the crib. Use a pack n play, then move them to a twin mattress on the floor when they grow out of that. We bedshared for 18 months and it was fabulous. By 3 weeks, I was sleeping 9+ hours at night, despite almost constant nursing. Dr. James McKenna is the best resource for bedsharing safety. Around 18 months we moved our girl to her own room with her own bed and night weaned her. It was a relatively easy adjustment for everyone.
Financial Security. This is a FI forum, so it should go without saying that despite our best efforts, kids get sick. They get hurt. Chronic conditions arise. Job losses happen. Take a look at your health insurance and figure out what a two night hospital stay would cost you. For most people with a $1,000 individual deductible and 20% coinsurance, this could very easily run northwards of $5,000. What about copays for office visits and preventive care? The flu followed by an ear infection can mean multiple office visits and prescriptions. Now is a good time to put an extra $5,000-$10,000 in your emergency fund, just to be on the safe side. Are you planning on contributing to a college fund? Look at 529s and UGMAs. Figure out how much you can contribute monthly or annually and start making adjustments to your monthly budget now.
NICE TO HAVE
Stroller. This depends on your lifestyle. We have a jogging stroller which I use several times each week to go for runs or we use when we know we'll be facing "mommy terrain". We have a smaller, lighter stroller for travel, tight spaces, and public transit. For really tight spaces, we use the baby carrier. I have chronic back issues from a horse riding accident when I was 22, so I can't Babywear for more than about two hours at a time. Since my husband often travels for weeks at a time, if I ever want to leave the house on my own for more than two hours I usually have to take a stroller. So for us, it's a need. It's not a need for everyone. in my late teens and early 20s I contributed significantly to raising my nieces and nephews. With that, I handled enough pieces of Graco plastic crap to know that one would never enter my house. Ever. Yes, we dropped some $$$ on both of our strollers, but they are SO worth it for the freedom they give me and how much easier they are to use than cheap ones. Everyone who pushes our strollers for the first time invariably says "OMG this thing is amazing! It's like pushing a cloud!" Worth every penny, both of them.
Everything else.
Barring the Zombie Apocalypse, stores will still be open after your baby is born. They will still sell baby stuff. I'm pretty sure Target will survive the Apocalypse anyway. Set aside a few hundred dollars for random stuff you'll need in the first few months. Babies like one kind of pacifier or nipple, but not another. You'll run out of diapers or formula or you'll need rash cream. You'll figure out what works and you can always order from Amazon without leaving your house. Go simple before the baby is born. Hold onto all the free stuff you get to see what you might want or need. Learn about your baby's personality and your own parenting style before you invest in all that crap. But mostly, just enjoy being a parent. It's the most rewarding thing in life.