I have two that I love & highly recommend. I'm not sure about affordable, but they've been worth every penny. They both have vertical bars, so your baby can't climb over.
I have this one set up in the hallway. You just press the footpedal and the gate opens - no having to step over or take down when I go down the hall.
The First Years Hands Free Gate - Gates & Doors - Dog - PetSmart
I have this much larger one set up on the other side of the kitchen, similar to the photo where they have it going from wall to wall. Between the two, my babies are contained to the kitchen & dining areas only when I'm not home.
Convertible Pet Yard - Crates & Kennels - Dog - PetSmart
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He is your friend, your partner, your defender, your dog. You are his life, his love, his leader. He will be yours, faithful and true, to the last beat of his heart. You owe it to him to be worthy of such devotion. -- Author Unknown