R.Y.
Well, I have a crib from my aunt that was used by 2 cousins and my 2 kids and had no problems. If you feel strongly I can see a case for getting a new mattress. On the other hand I was just as glad to have a used mattress since I heard stories about new mattresses releasing harmful chemicals. But I trusted my relatives and on one smoked at home or anything like that. I bought new bedding but if you got some used you could just wash in hot water or keep it for "emergencies". Definitely get enough to layer on the sheet and waterproof mattress pad a few times to save work in the middle of the night. I did that with my kids and never got down to the bottom layer with either kid. The t-shirt fabric sheets stretch and are way easier to get on and off.