Okay kiddo, let me explain what "bang for the buck" means.
Imagine you saved some money to buy toys, but you can only buy one toy. There are many toys to choose from and they all have different prices.
Now, you want to find the best toy that gives you the most fun for the money you saved. So, you ask yourself which toy gives you the most "bang for the buck".
"Bang" means how great the toy is and how much you enjoy playing with it. "Buck" means how much money you spend on the toy.
So, when you say a toy has good "bang for the buck", it means it is a really exciting toy that doesn't cost too much. You get a lot of fun for the money you spend.
It's important to find things that have good "bang for the buck" because you don't want to spend too much money on something that isn't worth it. It's like getting the most value for your money!