If you stand on line to buy an iPhone Friday, some of the people around you could be paid to be there, buying iPhones for other people.

Why do they do it? "Money, pure and simple," said Kim Foster, of Chicago, Ill. "Just bought my first home and money is very tight, as you could imagine. I've heard of people doing this for other items, Xbox, etc., and thought it was a very smart idea. So I thought I'd give it a go."

Line-standers include Brandon Phenix, of Wrigleyville, Chicago. "I'm a fourth-grade teacher and I have nothing to do this week, and I thought this would be good way to earn money," he said. He made sure to include his profession in the ad, which, he said, makes the ad stand out. "The keywords make people think I'm trustworthy -- which I am," he said.

He said Wednesday he's gotten five calls in response to his Craigslist posting, and bidding for his services has gone up to $350. He expects to charge $500 when the bidding war is done.

Phenix's biggest concern: People cutting in line. "I'm specifically looking for a place where there's less people, and less likelihood of that happening," Phenix said. He said he called around to see if local stores were planning extra security or giving out numbers to waiting customers, but found they weren't.

One Las Vegas line-stander has a plan for cutters. "We're aggressive when it comes to line cutters," says the ad. "(We will cap any mother** that tries to cut in line )." Yikes.

Line-standing is a grueling business, requiring specialized skills and equipment and (according to that Las Vegas ad) a killer instinct. Many line-sitters are planning on bringing, appropriately enough, iPods to keep themselves entertained.

Foster quips that she has "top secret" waiting techniques, and may bring her dog.

"Bring a chair, bring lots of food, a book, just make sure you're comfortable," said Joshua Palmer, 16, who lives on the east side of San Francisco Bay.

Palmer is charging $400 to hold a place in line for a man who wants to buy the iPhone as a gift for his son's birthday. Palmer works part-time at Moonstruck, a cafe that sells high-end chocolate. He also has experience buying past high-demand electronic products like the Nintendo Wii and Sony PS3, and selling them at a markup on eBay. That's not possible with the iPhone, because he's too young to sign up for the service plan, he said.

And if you don't want to pay someone to wait in line for you, you can pay someone to create a diversion