There are lower cost options. We did have to buy a new car (replaced a Toyota 4Runner with a Ford F150 Crew Cab) - our other car was already a Honda Odyssey -

There are lower cost options. We did have to buy a new car (replaced a Toyota 4Runner with a Ford F150 Crew Cab) - our other car was already a Honda Odyssey - but all three of our kids share a bedroom and I bought a lightweight Helinox cot that we use in hotel rooms when we can't find a place with 2x queen/king + sofa bed.