What we've needed:
Breast pump/nipples/bottles/pumping gear.
Food- it's not a lot quantity wise, but I've noticed our food bill has increased by about $30/month since Noah started eating more solid food.
Spoons-- though Noah is already fine with regular spoons
Food is something we're still figuring out. For the first six months, we relied exclusively on breast milk. Thereafter, it was breastmilk and a mix of lots of foods.
For this, since I returned to work at 12 weeks, I've been using the Medela Pump-in-Style Breast Pump-- Bought second hand from someone on Craigslist. I also got bottles, caps tubing etc, from the same person. So I just needed to buy nipples. This is a somewhat controversial subject but if you're pondering whether to do this, let me know and I can talk you through the risks. Not ignoring those risks or downplaying concerns you might have, there are financial and environmental benefits to going used, and everything apart from the pump itself can be sterilized. Having used the pump for a while, I feel confident that the risks of the pump mechanism actually getting milk in it are minimal.
I didn't end up reading anything about baby food, because I feel like I would have gotten rigid and stressed, and because I feel like I've learned a lot about food more gradually and organically over the past few years, from nutrition to developing a philosophy around food. I heeded the big advice around baby foods: no milk, no peanuts, no strawberries, and no honey until age one, and introduce other full-cream dairy around nine months. Otherwise, we've tried to not give Noah any foods with an ingredient list.
We grind grains (oats, brown rice, quinoa) in the coffee grinder, and Noah usually eats some kind of grain, some fruits, and some vegetables (and occasionally lentils and meat) every day. I make our yoghurt (I say that nonchalantly, as if I've been doing it forever, when in reality I learned maybe three months ago, and announced it proudly on this blog). Glass jars have been great for keeping the baby food process simple. By making a lot of food at once and freezing the leftovers in small jars, we're not stuck cooking or preparing every single meal. I tried ice cube trays but I found small jars worked better. We're careful about limiting salt consumption, but otherwise he usually has a bit of what we're eating, and if he doesn't eat much then he'll have something made especially for him. His six teeth are pretty sharp, and his digestive system is developing fast, so we're able to grind grains pretty coarsely at this point.