Sorry i should have been more clear, im in England, im not sure what centile as he hasn’t been measured recently he’s getting measured next week! A mini countryman is the car it would go in and I’m assuming her budget would be £200 but im really not sure xx
I would try and weigh him and measure him - you can do it yourself with bathroom scales and a tape measure - because some cheaper seats aren’t as long lasting but will be fine if little one is on lower centiles. Also check with your MIL how much she’s able to spend. And whether she is happy to leave the seat in the car when it’s not in use.
You may want to check weight requirements, age 4 seems extensive my son reached weight before height and his legs were cramped so we had to switch to forward facing. It gave us much car rides, less fuss.
@Siedah there are some great rear facing seats now that allow loads of leg room for older children, but they’re usually on the more expensive end of things
Joie makes some good car seats on your side of the pond. They've only just started branching out to make seats here in the US
Definitely check both height and weight maximums for it. My son is also 15 months. He's a petite little boy though, so he can easily get to at least 4 by weight of both his seats, as he's more likely to max out the length well before he maxed out weight max for it
For a more budget seat. The joie everystage R129 is a great seat. It rear faces to 22kg or 105cm, so if your little one isn’t too tall then that would keep them rear facing for a while. It’s often recommended as a great budget seat for grandparents cars etc x
What country are you in? What centiles is your little one on for weight and height? What car has the seat got to go in? What counts as “cheap” to you?