AURORA, Colo. -- The world's oldest profession is going high-tech. 'Johns' can now shop for prostitutes on the Internet.

One woman showed police just how lucrative this illegal underworld can be, 7NEWS reported.

It started in August 2003. That's when a nanny was watching two kids while police said their mother was upstairs, taking money for sex. That nanny called Aurora police and told them what was happening.

The phone call launched a year-long investigation that eventually led detectives to the woman's Internet site and to a Greenwood Village sports bar.

Police sent undercover officers into the bar on Halloween. The officers said they saw customers and working girls wishing each other a happy Halloween, and more.

"(It was) a wide open, in the open party, and everyone who was there knew what was going on," said an undercover Aurora police detective who only wanted to go by his last name of Sellman.

The gathering was a chance to see, touch and hire the prostitute of your choice, Sellman said.

"I don't think people understand that there's a whole subculture going on right now," he said.

Even the police were shocked at what they called a "prostitution convention" -- a world that Sylvia Prince had showed them.

The 27-year-old was entertaining up to five men a day at her upscale southeast Aurora townhome, while a nanny watched her two kids, a boy aged 6 and a 2-year-old girl, police said.

After her first arrest in December of 2003, Prince got an ultimatum:

"If she were arrested again, her children would be taken from her," said Detective Larry Martinez, with the Aurora Police Department. "She was willing to take that risk."

Minutes after her second arrest, police said she was on the phone with an undercover officer. They recorded the phone conversation.

Woman: "You don't have to bring the money in an envelope for me. Just keep it in your wallet."

Man: "Oh, OK."

Woman: "And then pay me after the session, OK?"

Man: "OK"

Walking the streets is passe. Police said today's prostitutes use magazines, business cards and especially the Internet to sell themselves for up to $250 a hour.

At some sites, customers post online reviews of the women as a crass form of quality control.

Police said the prostitutes are hooked on the money and the fame.

"They start to see themselves as almost superstars," said Sellman.

Prince did 30 days in jail and is now serving one year probation, based on three prostitution convictions. She also lost custody of her children, who are now staying with family.

Another woman was also arrested as a result of the investigation.

The Edge sports bar, could lose its liquor license, too. That's because Greenwood Village police also attended those erotic parties undercover in August and in Halloween of 2004, 7NEWS reported.