Inexpensive car seat that transforms from baby-toddler-booster?

We’d like to get a car seat that grows adjusts with baby for my parents place.

My folks live an airplane ride away. We visit a few times a year and sometimes it will just be me and baby traveling alone so we’d like to get a car seat there that can grow/ transform with baby that we don’t need to lug back and forth.

Baby is currently 4 months, about 18 lbs and has very good head neck control. The car seat would stay in the car so no need to unlatch a seat from a base with a carrier

handle. We’d rather get one that transforms from baby to toddler to booster seat.

Looking for something around $150 or less. Ideally less than $100 but not sure that’s possible.

What do you like??

Thanks in advance!!