C.
Hi Y.. I hope this does not come across as rude. You really should not use used carseats unless they have come from someone you would trust your childs life with. There are a couple of reason for that. First of all, you really have no way of knowing (for 100%) that the carseat has never been in an accident. This is extremely important, because even a seemingly minor accident can cause damage to a carseat that cannot be seen. Another reason is that you don't know if proper care was taken of the seat. A lot of people do not know that, when cleaning the carseats, you should not wash the harness. Washing the harness weakens it, making it more likely that that the seat could fail in an accident. Here is a checklist that you can use if you decide to go with a used seat, but you need to make sure that you can answer each question w/ 100% confidence. http://www.cpsafety.com/articles/usedseat.aspx
There is a great resource out there for people who can not afford to get a carseat for their child. You attend a 1 hour carseat information class, sign a couple of papers, and walk out with a BRAND NEW CARSEAT. Here is the website for that. http://www.dshs.state.tx.us/saferiders/distribution.shtm
If you can, go look at WalMart or Target. The Cosco Scenera is very affordable, under $50. It is a great little seat too.
Anyhow, like I said I hope this didn't come across as rude. This was information that I didn't know before and wish someone would have told me. Good luck w/ getting a seat!