Baby OxyClean spray is a god send.. a must-have for us; I haven't wrecked any clothes with formula or anything yet!
I think the expense is what you make it TBH.
I really recommend bibs that have a plastic type of back- the all fabric bibs get soaked and leak through to clothing.
If you're going to have bottles you'll need a bottle brush also.
Also recommend a mobile for the crib!!
Diaper bag
Separate thermometer for baby
Rocking chair or glider
Outlet caps (the plugs you put in the electrical outlets so baby can't put fingers/toys in there)
Nightlight
BATTERIES. Baby toys all use batteries it seems lol and if your baby takes to his/her bouncer.. you don't want to be without. Monitors take batteries too.. so have them on hand.
Of course a camera!!