New: underwear, pj's, socks, bottles, pacifiers and stuff that are frequently washed and used directly on baby's body
Don't mind second hand: furniture, jackets,baby not so essential gadgets and toys toys toys!
I don't buy anything new for babies except car seats. They outgrow stuff so fast that its not worth paying full price.
I have bought several things used but carseats are one thing I wouldn't unless you know and trust the person. You never know if the carseat has been in an accident causing damage.
I think the success of buying 2nd hand really depends on the area you live. If you live in an affluent or surbaban area where people buy bugaboo strollers and designer baby clothes and nicer items in general your thrift/consignment store hunt will Be a lot easier than if you live in a rural or low cost of living area where people tend to buy bargain brands or recycle used items. It also depends on your standards and if your squeamish about germs and such. I don't think there's anything wrong with buying used; the baby doesn't know it's used and doesn't care. You can clean and disenfect things, and really, you're probably only going to use Most products for about a year before they're outgrown. I'm more of an in store bargain shopper but I did buy a few things 2nd hand.