Cheap and easy are all relative terms. Have you considered another snake species or is your daughter set on a BP? Maybe a colubrid of some sort would be better?
I recently went thru the exact same exercise of working with my daughter on fulfilling her wish of snake ownership. We thought a BP was the way to go since it's the go-to "beginner" snake, and they're just so beautiful. But after months of research, we settled on something completely different.
We wanted more a display animal so we could take advantage of a large glass tank. We wanted a snake with a more outgoing personality, which can be hit & miss with beeps. And we were turned off by the more specific and complex husbandry needs of a beep. We ended up going with a Russian Rat. While (arguably) not as beautiful as a ball, he fit the more important traits we were looking for in a pet.
So you've got options, just saying!