I don't because I watch two other boys as well - One is a teenager whom I don't drive much but when I do he rides in front and the other is 6.5 and rides in a Graco Turbo.
She puts her on the pass. side because that's where I have always put her - also she is VERY squirmy and doesn't much like the car so it's easier on the side then the middle. She will try out my Radian when I get it to see if if fits, but we posted to see if anyone who had the car had a CS in it they really like.
The budget will depend on how well the car seat fits, how long it can last and how much clearance there is to get her in and out of the car. So really there isn't a budget as long as we get a seat that fits her and the car great
. but they would like to spend as little as possible of course.
My sister had received a new RF CS as a baby gift (a Evenflo Momentum 65) and tried it but the gap between the top of the door and the CS was so small we had to slid her in feet or head first then swivel her around. This won't work because she usually resists getting in the car (she can't walk or crawl yet to get in herself). The momentum CS was put in my BIL car because she won't ride in it as much so it is less of an issue and it fit a little better (He drives a 2011 Hyundai Sonata).