She has a small car (two door) so something light and small and not super $$. She is willing to buy it if I pick it out and tell her where to get it so I am grateful for that. We have the Britax Marathon in our car but I don't want another one of those.
Maybe Evenflo? I know there were other posts like this so pardon the repetition.
Re: convertible car seat for Nana's car?
We bought two Evenflo Tributes for our babysitters (DD isn't in day care, she goes to either DH's aunt's house or our friends' house during the day, so we bought them both car seats). And then my mom and MIL both also bought them. They're inexpensive and very basic, but DD doesn't spend much time in their cars, and has been perfectly happy in those seats for 6 months now. DH and I have Britax Marathons in our cars too.
Yup, my kid has 6 car seats.