NEW YORK (CNN/Money) - Advertisers are writing checks for $2.25 million for each 30-second spot on this year's Super Bowl. That's a bargain.

At first glance, paying $75,000 a second may seem like a staggering amount. But the viewership it buys is vast. Last year's game, when ads went for $2.1 million, worked out to a cost of $23.70 per thousand viewers (a formula known as CPM).

That is far less than it costs to advertise elsewhere. For the series finale of "Friends," for example, NBC will charge about $2 million for a spot, but deliver an audience that's about 10 to 15 percent smaller than the Super Bowl's.

The cheapest a television advertiser is likely to pay per viewer is about $10 per thousand for a low-rated prime time show. CPM rates of $16 aren't unusual.

"There's a little bit of a premium (for Super Bowl ads)," said Jack Myers, an expert on advertising spending. "But if you're trying to reach men 18 to 49, it's a fairly efficient vehicle."

More important than the size of the audience is the attention the ads get. There is only one day a year when advertisers can be sure their spots are being watched -- and it won't be when America says goodbye to Ross, Rachel and the gang.

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A survey by online marketing firm InsightExpress found that 58 percent of those surveyed pay more attention to the Super Bowl ads than they do typical ads. In fact, fully 25 percent said they are more interested in the commercials than the game itself.

"I suspect the spots' viewership is significantly higher than on typical programming because of the buzz," said InsightExpress president Lee Smith. "Here, they actually want to see the spots."

Many people -- 21.7 percent of those surveyed -- have even gone online to view the ads after the game.

This year, both USA Today and CNN's corporate cousins at America Online will be conducting polls of the favorite ads after the game. You can even place a bet on what sponsor will win the most popular ad title from the latter.

This year is the 20th anniversary of the famous "1984" ad for the Macintosh computer. Though Apple only paid to air once, chances are you remember it far better than the game (a 38-9 thumping by the Raiders over the Redskins).

Even less-seminal Super Bowl ads are the subject of post-game discussions for days. When people talk about the last episode of "Friends," they won't be chatting about the sponsors. That $2 million just isn't going to go as far.

CBS has 60 commercial spots available for this Sunday's game, but it could see an even bigger pay day if the game becomes the first to go into overtime.

This NFL post-season has already seen a record three playoff games go into sudden death. But the Super Bowl has had far more blowouts than close games. Only a handful have been competitive down to the last play.

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An overtime game "would be everybody's dream," said ad buyer Andrew Donchin. "Even in blowouts, most years the game has kept its ratings near the end. It would have to go way up during an overtime."

Networks generally offer a slight discount to sell the last few available spots, often near the end of the game when advertisers might worry that audience is at risk of slipping.

John Boguz, senior vice president of sales at CBS Sports says potential overtime spots are not sold at a premium. He won't disclose who has locked up the possibly coveted spots, but they are sold just in case.

Both the Panthers and Patriots will lose money on their trip to Houston this year.

In the other team sports, a trip to the championship game means a healthy bonus from the league, plus extra concessions sales and likely greater ticket sales the following season.

But that's not the case in the revenue-sharing National Football League, the most successful socialist state ever to exist on earth.

The league gives a small stipend for attending the game, but it doesn't come close to the expense of moving a franchise to a neutral site for two weeks. And since most revenue is split evenly between all the teams, any ticket-sale bump the Pats or Cats see won't stay in their pockets.

The team that most likely got the most economic gain from this year's game is the expansion Houston Texans, who got a higher price on the advertising signs sales at Reliant Stadium because it is the site of Super Bowl XXXVIII.

Ad dollars are so sacred in the NFL that even the revenue-sharing beast can't touch them.