If you do decide to use a "used" car seat or one that is given to you, just please make sure to find an owner's manual somewhere. I know you can get them online at
Graco's website if you use their car seats. I have watched a friend misuse her car seat because she got it from her sister who doesn't have an owner's manual anymore. That is the scariest part about using a car seat that you didn't buy new, is that you don't know all of the instructions for it. That's just my thoughts on it!