I almost never tell people what to buy and not buy because we are all different AND all children are different as well. One child might love something and the other one would hate it. So that said, I am going to say what I have found useful just in case there's anyone out there like me.
I was told "Don't buy a changing table. You will never use it."
My son is 3 years old and I am STILL using my changing table. I used it to change him on. But I also used it to keep certain things out of his reach so he could play in his room. Now, I use it as a shelving unit for his toys. It has been so practical and so useful!
I was told "A wipe warmer is a waste of money."
Well my son was traumatized by diaper changes as a baby and having a warm wipe helped ease the process for him. It helped making it more relaxing. I want to buy every new parent one. But, see, we're all different.
I am glad we purchased a pack'n'play with a bassinet because it was useful for a very long time and we can use it again this time around.
I loved my boppy pillows. I still have them.
I was told that bouncers and swings are the best items. They ended up being dust-collectors in my house. My child had reflux and could not handle them. The bouncer aggravated his reflux even more. I'd wait until after baby is born to make either of those purchases. This time around, I'm looking for a swing that is flatter and lays back more as my son tried a friend's swing like that out when he was little and loved it. But you just won't know what baby will or won't like.
I wouldn't buy most of the bigger stuff (like jumpers, exersaucers, etc.) before having the baby this time around. The baby won't use it for months, and it takes up space.
I'm trying to think if there's anything I feel like we really wasted money on. The only thing I can think of was this swing that was supposed to transition to a high-chair, then a chair. It was a waste to me. The swing didn't work well at all. It was a headache to transition it and the parts took up a ton of space in the house.
But, like I said at the beginning, I am very reluctant to tell people what to buy or not buy because everyone will have a different experience. And what was a waste for one person was a treasure for me and vise versa.
Oh and just to be funny, if you have a child who spits up a lot, you might want to invest in a poncho.