The best toy we ever bought Ace was a slingshot ball. There is more than one brand of this toy such as the Hyper Pet Flying Duck. It’s great because when you have a dog that wants to play fetch forever, the ball goes a lot further with the slingshot power than it does when an average person throws it. Plus, it takes very little effort on your part and the dog has to run a lot further and will get a better workout.
Of course, my mutt is totally fixated on this ball, even worse than a tennis ball. I suggest limiting the time a dog plays with any ball to 20 minutes or so and then putting it away. It’s better to set limits on all toys anyway to enforce rules and limitations and so the toys don’t lose their appeal. Ace can rip these things apart within minutes, so they aren’t really meant for chewing, just fetch.
These toys are also great because they float in water and are easy to find in the snow, tall grass or water because they are very bright, with a hot orange band. Try one out sometime. They come in at least two sizes and are cheap entertainment. They come in two packs between $5 and $10. Ace highly recommends the Go-Frrr ball.