As a child passenger safety technician/instructor, it grieves me to see USED car seats for sale on e-bay.  For the safety and protection of our children, I submit the following information:

1. car seats have a six year life.  Most seats even have the expiration date molded into the shell near the bottom of the seat.  car seat shells are mostly comprised of plastic, and years of exposure to heat & cold in your vehicle can begin to compromise its integrity.  The same for the harnesses.  They have some plastic in them as well, and over time they will begin to fray and lose their integrity.  In many states in the US, it is considered a child restraint violation to use a seat that is more than six years old.  I train IN police officers for a living, to instantly identify child restraint violations, and help parents know how to properly restrain their children. But we ALL need to do our part to protect them. 

2. car seats are a "one use item".  If the car seat has been in a crash (even a parking lot fender-bender), it needs to be replaced.  How does a buyer know for SURE that the car seat they're buying hasn't been in a minor crash?  Many, many people buy second hand seats (which is what these seats you're selling truly are), and children are injured and killed because the seat cannot perform the way it's supposed to the second time around.

3.  Most families do not even know if a second hand seat has all it's parts, if the seat is free from recall (you can check with NHTSA) see if the seat has actually been recalled. If there is a manufacture problem with the seat, and the parents are not aware, again, it could result in an injured child.

With all this being said, I'm sure you could stand by your "caveat emptor" attitude, and say that it's the buyer's responsibility to check all that out.  But we're talking about our children.  The WORLD'S children.  E-bay should take a stand to say that they won't allow anyone to sell a used car seat.  Selling the new ones is great.  As long as it's still sealed in the box, with the the registration card still attached - I'm all for it.  I saw some great seats on here.  But, I also contacted four people last night, because they were selling seats that were expired.  All because I just simply asked them what the manufacture date of the seat was. Three of those seats were Evenflo "On My Way" infant seats, which are on NHTSA's recall list.

One sweet, gracious woman thanked me for telling her that because she didn't know.  That could have been a life saved.  See what I mean?

You should have a certified CPS Technician reviewing ANY seat that is to be auctioned on e-bay.  For your own liability as well.  You know as well as I do that if a child dies because the car seat that MOM bought on e-bay failed due to expiration, a previous crash, missing parts, etc... you can bet that e-bay will be named in the lawsuit.

Thanks for your consideration,

Sue, Child Passenger Safety Technician/Instructor