Another word of advice to car seat purchasers: Never ever, ever buy a used car seat unless you are absolutely, 100% positive that it has never, ever ever been in a car accident of any kind. Even if the car seat looks solid, it could have hairline breaks inside the plastic framing which will compromise its effectiveness in future crashes.
My philosophy is that a car seat is worth the extra expense for good quality protection. Even if we are safe drivers with baby inside, we never know about the other wacko-s on the road.
When you get the car seat, be sure to send off the postage-paid postcard and "register" your seat with the manufacturer. That way, if the car seat is recalled, the maker will notify you and possible offer remediation.