My mom watches LO at least one day a week and asked me to recommend a car seat for her car. In the past she has just borrowed our car, but she would prefer to drive her own car now that he is older and there are more places she wants to take him.

Ideally it should be:
- easy to install (she is convinced she will be taking it in and out often - though I have no idea why)
- not too heavy (though can carry 27lb DS around so she's no weakling)
- not too expensive (I'd like to buy it for her and would rather not spend $300)

Also must be convertible - DS is 17 months and we plan to rear face quite a while longer.

FWIW we currently have a Britax Marathon (old kind with latch/seatbelt install) and Britax Boulevard Clicktight.