We bought one of these balls from Asda when I took my Grandmother shopping because as usual my daughter asked for it, I said no so my grandmother bought her it anyway! The balls only cost £3 each so it wasn't too much money so better than some of the things she lets her have. This type of balls can be bought from lots of differnet places, supermarkets and pound shops do seem to sell them the cheapest however.
The balls are available in just about every colour you could think of although at the time Asda had blue, pink, green and black, I knew my daughter would pick the pink one which she did however we did have to stand for 5 minutes whilst she made the decision, how hard it must be to be 4. The balls are made of rubber and are filled with clear gel complete with little bits of glitter inside, the gel allows the glitter to swirl around inside when the ball is bounced which my daughter thinks is great.
The ball is about 4cm in diameter which is goo as any smaller and I would have to be concerned about my youngest daughter swallowing it which is why my eldest daughter hasn't ever been allowed the little bouncy balls that come out of gumball machine.
The ball is strong and bounces well almost too well as we do sometimes have to tell our daughter to calm down with it, our youngest daughter likes to chase the ball up the room and we end up with fights over it, god help us in a year or two. Sometimes if the weather is ok my daughter will take the ball outside so she can play with it in peace meaning it gets covered in mud but the ball is easy to clean with a simple wipe over.
For £3 this ball has given both my girls loads of fun and I would recommend it just think I may have to buy a second one to stop the fights.