I love the chuck-it, and if you have any kind of upper body strength, you can REALLY hurl that ball. 10 good throws with the chuckit takes the edge off Eve's need to run.
The rubber balls they sell for the chuck-it are great, soft and very durable for fetching, though I doubt they'd hold up to Eve's teeth if she played with them like her orbee toys.
Planet dog makes "tennis ball" toys out of orbee material - Eve has three of them. They fit the chuck-it poorly, though.