What Car? Q&A - Are used child seats safe?
A: You should never buy a second-hand child seat - either on the internet or anywhere else.
This is because it's impossible to tell simply by looking at it whether a child seat has been damaged.
If it has, the seat might not provide adequate protection to your child in the event of an accident.
Also, the seat might not come with a user manual. Without proper instructions on how to fit it to your vehicle, you could compromise its effectiveness by fitting it incorrectly.