Since you are looking into a kid's ball I may as well ad my 2 cents for you.
Most "kid's" balls are as stated above, a plastic ball with a pancake weight block, some with a cartoon character engraved, or just multi colored. The cost of these balls are also usually on the low end.
Considering that you can get most of these balls at our local pro shops for between $45 to $65 (which includes fitting, drilling, and any future minor adjustments such as enlarging the holes free), you may just be better off utilizing the local shop. If you add up the cost of the ball (VERY low profit margins on these) shipping, then add the drilling & fitting to your internet purchase, it will probably be cheaper buying locally.
On higher end purchases you can often save money on the internet purchases, but it probably will not be cheaper for a kid's ball.
Your local shop should be glad to oder any ball you desire, and often will have a ball/bag combo deal for kids as well.
Best of luck, and happy bowling with yout kid.
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