Booster seat help

My daughter is 7 years old. She’s 41 pounds but I’m not too sure how tall. I’d say around 3’7. She still in a car seat. Is she big enough to get out of one completely or should she be in a booster? If she needs one then What is the best one to get from Amazon ? I found a really cheap one for 25 bucks. I don’t have much money at all but I don’t want to get a cheap one like that.