Consumers trying to keep their budgets balanced will be dismayed to find that keeping up with the Joneses is getting pricier as the global middle class expands.
Economists generally consider the middle class to be people with the financial resources to make discretionary and small luxury purchases—from an automobile to concert tickets. By that broad brush, about 2 billion worldwide qualify, said Jack Plunkett, CEO of Plunkett Research.
By 2030, that number will balloon to 5 billion, with many of the newcomers in developing countries such as India, China and Brazil.
Consumer spending in Brazil, Russia, India and China accounted for 8.1 percent of global gross domestic product in 2010, according to IHS Global Insight. It is expected to reach 12 percent by 2015. U.S. consumption as a percentage of GDP peaked at 22 percent in 2002 and is expected to be roughly 14 percent by 2015.
That emerging middle class pushes prices higher, because there are more people vying for resources and products. Rising wages, which help create a middle class, also inflate prices because goods are more expensive to produce, Plunkett said.
"The long-term effect is going to be pretty dramatic," he said.
Consumers are likely to notice first—and may have noticed already—with basic items such as groceries and gasoline.
"When people get a higher income, they want to eat more meat," said Chris Christopher, an economist with IHS Global Insight. Prices for a pound of ground chuck and whole chicken are up 20 percent and 28 percent, respectively, in the past five years, according to the Bureau of Labor Statistics.
In some cases, surging demand contributes to temporary shortages in supply. That happened recently with baby formula in China and a few years ago with rice worldwide, said Teri Gault, CEO of TheGroceryGame.com.
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The effect of the new middle class isn't limited to staples. It has pushed the needle on luxury items, as well, including designer fashion and premium alcohol.
Commodities such as diamonds and gold also have been affected, although global economic woes have put a temporary damper on the trend, Plunkett said.
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Diamond prices are down as much as 2 percent this year because of lower demand from India and China, according to brokerage firm ConvergEx.
U.S. consumers may also find themselves playing second fiddle to the middle classes in developing countries. Those first-time buyers provide a unique opportunity for manufacturers of everything from automobiles to cellphones to lock in brand loyalty, according to Christopher.
"Major corporations are taking notice of the global consumer rebalancing," he said. "They're trying to maximize sales."
That's likely to mean more products that are designed with that audience in mind or that are introduced abroad before the United States. In 2011, Dell, for example, launched the XPS 14Z laptop in China a month before it arrived stateside.
"This is unheard of before," he said. "It's a pretty strong shift."
—By CNBC.com's Kelli B. Grant. Follow her on Twitter @KelliGrant.