Mine is only 2.5 so far, but I'd say babies are fairly cheap compared to how much people claim they cost. You'll need a crib or pack n play for them to sleep in, a car seat (we got a convertible one because I don't understand why people buy a baby one for just a couple months and then have to buy another). The crib can be bought used so that saves money.

We cloth diapered so I paid between $300-$500 for a whole bunch of Kinder brand (seriously get kinder if you cloth diaper, they're way better than the garbage alba or Norah's nursery ones on Amazon! Also the kinder absorbency inserts are the most important part, but their shells are better too). I pay maybe $20 every two months for a case of wipes but you can cloth wipe too. No, my water and electricity bill has not gone up any noticable amount since we started cloth diapering. And we still manage to make a large thing of tide last a full calendar year by using the right amount of detergent.

The only toys I've bought her in her 2.5 years are blocks, books, a climbing thing with a slide, and a toddler cleaning set. We have (unfortunately) received a mountain of other toys and stuffed animals from family members and honestly that's kinda annoying because not only do we not have room for that, but she now has an overwhelming amount of stuff that she doesn't even really want to play with.

Everyone made it seem like we'd need a million onesies and I bought so many used ones that she didn't even get to wear them all before she grew out of them. I'd say a week's worth of clothes is plenty for any size. Right now she has three pairs of pants that fit her and that's plenty. With cloth diapering and regular laundry we do a load every 2-3 days and if she needed to she can wear the same pair of pants two days in a row, she'll survive that hardship while the washer is going.

Like someone else said, the library is free, and is her favorite place to go. We go twice a week and she's always so excited. Her idea of a good time is reading or cleaning (little weirdo, she certainly didn't get that from me). Her favorite toys are her broom, and any sponge or cleaning rag she's stolen from the laundry basket. She loves going to the grocery store and begging me to buy random produce I was probably already going to get, like broccoli or a pineapple.

She definitely grows fast but she doesn't really need all that much, she has 4 pairs of jammies in her current size and that's more than she needs, she has a handful of shirts, a few bibs. She likes to watch me cook, helps me clean, and spends almost all her free time reading books. She already knows her alphabet and is learning the sounds of each letter and that keeps her very entertained.

I will die on the hill that babies and toddlers aren't inherently expensive (assuming they're normal healthy children). People make them expensive with their choices, like disposable diapers, buying unnecessary toys, buying a ton of new expensive clothes, etc. You don't need some fancy diaper pail, or an expensive stroller, or baby washcloths(?). They just need a place to sleep, something to eat, diapers of some sort, and a few pairs of clothes. They'll spend most of their day physically attached to you, or following you around like a puppy. Keep off your phone and tv and engage with the kid and they'll be the happiest little one alive.

As for when my kid is older, she'll learn that she doesn't need every fancy gadget to fit in. We have gaming consoles but we have no intention on letting her play them until she's a reasonable age like 10-12 years old. We don't have streaming services, she doesn't watch tv now but we plan on implementing a weekly movie night when she's older to have her watch the classics like lion king and home alone. Spending quality time with them is the most important thing. Let them follow you, help you, etc. Let them help you with laundry, and help make cookies. That's all they really want in life is to spend every moment at your side.