The S&P 500 (SNPINDEX:^GSPC) counts among its ranks 500 of the most important U.S. companies. They're not always the biggest, but they represent a cross-section of the U.S. economy, with components in just about every industry you can find. Over time, the S&P 500 has climbed steadily, performing in line with America's long-term growth prospects. But some companies have done better than others, and choosing not to take measures like splitting their shares, the most successful have seen their share prices soar. Today, let's take a look at (NASDAQ:BKNG), Google (NASDAQ:GOOGL), and MasterCard (NYSE:MA), which among them have the three highest-priced shares in the S&P 500.

Source: The Motley Fool.

Making money from other people's spending
MasterCard might have gotten passed up to join the Dow Jones Industrials, but like its larger rival, the credit card network has benefited from the great rise in use of credit and debit cards both in the U.S. and around the world. As customers have felt more comfortable using electronic-payment systems rather than cash for their transactions, MasterCard has become one of the most successful middlemen in the economy, taking a cut from merchants in exchange for instant payment while sloughing off credit risk of cardholders' repayment onto issuing banks. That's how its shares have climbed to $734 from around $50 back in 2006.

Even though the U.S. card market is well-saturated, MasterCard has huge international growth opportunities. In its most recent quarter, MasterCard demonstrated the value of its global presence, reaping big rewards from the economic rebound in Europe. Emerging markets also represent a large opportunity for MasterCard, as many emerging economies still rely on cash transactions for the majority of their business. Combined with exploration of mobile-payment systems, MasterCard could see shares climb even further from their current levels.

Searching for a grand
Google just hit the $1,000-per-share mark last month, but investors have anticipated that rise for a long time. After going public less than a decade ago at $85 per share, Google has become the dominant online search engine, playing a vital role in most people's daily experience with the Internet. Along the way, Google has collected huge amounts of data that it has used in numerous ways, building its advertising revenue and increasingly fine-tuning its offerings to extend its reach.

Google's recent growth hinges on its mobile opportunity, with its Android operating system having become the most popular mobile operating system in the world. Lately, Google has started to ramp-up monetization of its mobile capabilities, and the innovative ways in which it's using its YouTube video service could continue to drive shares much higher than $1,016 in the years to come.

Flying higher leads the S&P at $1,073 per share, on the basis that Warren Buffett's Berkshire Hathaway only gained entrance to the index because of its lower-cost B shares. Priceline reached the key $1,000 a month before Google did, but the most amazing thing about Priceline is how it recovered from single-digit share prices in the aftermath of the tech bust to its current level.

Priceline's story is extraordinary, but it hinges on a combination of its distinctive innovation in the online portal space as well as behind-the-scenes strategic moves that cemented its leadership position. Most people know Priceline from its bid-based "name your own price" strategy, but much of Priceline's success has come from its foresight in building up an unmatched network of international hotels and travel service offerings that allowed it to gain global scope long before its rivals caught onto its strategy. As new CEO Darren Huston assumes the reins from Jeffery Boyd, Priceline will continue to fight to remain the leading player as travel transits to the mobile realm as well.