TDAP/Whooping Cough

I want my MIL to get the TDAP/Whooping cough vaccine so my LOndoesnt get sick bc I already know she's gonna be all in his face. I'm in the military and they just handle all of that, I'm not sure how to handle this type of stuff in the civilian world(please no judgement I've been in since 17), she doesn't have insurance and I offered to pay for it. Can any one help me out with how about she'd go and get it? Also anyone know about how much it'll cost?