It depends. For a general baby shower, I probably cap out at $25. Everyone else varies based on what I can afford at the time. I didn't get much for my older sister's babies, but I imagine I'll spend more on my younger sister and or give her hand-me-downs.
I don't send stuff to extended family most of the time. No one lives nearby. If I go to visit the baby, I'll definitely take something.
For me, it really depends on each individual relationship, not just the assumed one.