If you're getting a baby, the cave would probably be too big. Ball pythons are docile nocturnal creatures that like to hide in safe small hides. In the wild, they're usually easy prey, so they hide most of the time. In captivity, they like to hide in small tight hide spots. You can go buy commercial caves like that, but they're usually made for looks, and not so much for the pet itself. Your best bet would be to get a few cheap clay planter bottoms. Here's a quote from an earlier post of mine. It might help you out.

Quote Originally Posted by Cody
There's nothing wrong with the hides. They're just too big for him right now. I myself would swap them for two small clay pots with a hole knocked out for entrance.
Here's a site that helped me out when I was wondering about a cheap and efficient way to provide hides to my snake.

http://proexotics.com/FAQ_answers_Hide_Spots.html

And a video on how easy it is to make a hide spot.

http://proexotics.com/FAQ_answer_making_clay_hide.html