Giving your kids an allowance and requiring them to make their own purchases will save you money in the long run and keep your kids from acquiring more useless stuff. Here's how it works.
"Mom, can I have a bakagun?"
"How much do they cost?"
"I don't know. Can I have one?"
"Let's look up online how much they cost."
"The start kit costs $18.99. Do you have $18.99?"
"Okay, when you get $18.99 let me know and we'll go get a bakagun."
Your kids won't be happy at first, but after a while they'll get used to it. And chances are, they'll loose interest in the bakagun before they save the money or they may just save the money and buy it, but it will take weeks. In the meantime, they aren't buying anything else with their money.
When my boys wanted a Wii, we had them save up for the entire thing. They saved birthday money, report card money from Grammy, allowance, tooth fairy money and any other money they could. Then they held a yard sale and sold a lot of their toys. Not only did toys they weren't using find new homes, they realized how much stuff they could do without. They also understand the value if that Wii a lot more than if we'd handed it to them. They take good care of it.
My boys don't buy everything. We buy their clothes, food and other necessities, of course. We treat them once in a while, too, and buy them birthday and Christmas presents. But they need to figure out how to get most of their toys throughout the year. My six year old, who wanted the bakaguns ended up trading his Ben 10 watch that he had paid for himself to get them.
The result, they have less toys (and don't seem unhappy about it), they leave a lighter footprint on the earth, and my husband and I can use our money for other things - like the gallons of organic milk we go through each week.