1. 12 Tuff Balls - Industrial Strength Dog Toys, Standard Size 2.5" (Click Link to Check Price on Amazon)
Editor's Rating : 9.5 out of 10
Tuff Ball Bulk Dog Toy, 12-packExtra thick natural rubber walls give extra durability and bounce

2. Tourna Mesh Carry Bag of 18 Tennis Balls (Click Link to Check Price on Amazon)
Editor's Rating : 9.5 out of 10
REUSABLE MESH CARRY BAG. Tourna balls come in a convenient reusable and closeable mesh bag for easy transport and storage.TOURNA PRESSURLESS BALLS NEVER LOSE THEIR BOUNCE. Regular tennis balls go flat over time, even if you don't use them. These balls will have the same consistent bounce for the life of the ball.

3. Used Tennis Balls (Click Link to Check Price on Amazon)
Editor's Rating : 9.2 out of 10
25 clean used tennis balls for tennis or baseball practice or for your dog.25 balls

4. (6 Pack) Tuff Ball Bulk Dog Toy (Click Link to Check Price on Amazon)
Editor's Rating : 9.9 out of 10
Tuff Ball Bulk Dog Toy, 6-pack(Size Small 1.8")For small dogs

5. OMorc Pressureless Tennis Balls - 12 Balls with Mesh Carrying Bag - Great For Lessons, Practice, Throwing Machines & Playing With Pets (Click Link to Check Price on Amazon)
Editor's Rating : 9.5 out of 10
Premium Quality. Made of high quality polyester fiber and rubber, our tennis balls offer excellent wear-resistance, pilling-resistance and playability. Last a long time with high performance.Superior Bounce. Our pressureless tennis balls maintain perfect and balanced bounce with thicker rubber shell that prevents from going flat. They get bouncy over time unlike those regular balls.