Our first was a boy and second a girl so mostly we just bought clothes.
When DS2 came along I had lent a heap of DS1 baby clothes out to a friend and some never came back (plus they were different seasons) So had to buy more boys stuff.
With each baby I've bough a special outfit just for them to come home from hospital.

Replaced worn and stained wraps and chuck rags.

With DS3 we bought a new pram (with tddler seat) as our old one was well used (and the dog chewed on part of the newborn insert cushion)
and the capsule that matches.

Bottles and teats
New breast pads (washable)