Are extra carseat bases worth it?

Natasha • 👰06.15 👶10.16 🤰06.20
We got a Graco click connect car seat/ travel system. We have 2 cars and it would be helpful for my MIL to have a connector as well. Is it worth it to buy 2 extra bases ( they are about $90 each) or just transfer the base if we are using another vehicle?