So once it gets too heavy you'll switch to a convertible, why would you want to lose the ease of keeping the baby in the carseat when you go out once they hit just 22 pounds?
And you don't need a Chicco, there are plenty of cheaper alternatives.
I have no problem carrying the baby in the car seat till 35 lb, or whatever the heaviest limit is for rear-facing. But my wife, who will be making the most use of it , feels that the weight and unwieldiness of carrying a 25 lb baby in a car seat is a bigger inconvenience than the added convenience of not having to take the baby in and out of the seat.
As far as price, we bought the Graco 22 at $75, and in the pattern my wife wanted. The Graco 30 is $105 for the cheapest pattern. And obviously the price climbs for the 32 or 35. So it's not a question of brand. Any brands 22 lb car seat will be significantly cheaper than its 30 or more lb car seat.