NEW YORK (Reuters) - Deal or no deal? An online exchange between a woman looking for a husband who earns more than $500,000 a year and a mystery Wall Street banker, who assessed her potential for romance as a business deal, has cause quite an Internet stir.

The anonymous 25-year-old woman recently posted an ad on the free online New York community Web site Craigslist, http://newyork.craigslist.org/, appealing for advice on how to find a wealthy husband.

"I know how that sounds, but keep in mind that a million a year is middle class in New York City, so I don't think I'm overreaching at all," the woman, who described herself as "spectacularly beautiful" and "superficial," wrote.

"I dated a business man who makes average around 200 - 250. But that's where I seem to hit a roadblock. $250,000 won't get me to Central Park West," she said, asking questions like "where do rich single men hang out?"

The mystery banker, who said he fit the bill, offered the woman an analysis of her predicament, describing it as "plain and simple a crappy business deal."

"Your looks will fade and my money will likely continue into perpetuity , in fact, it is very likely that my income increases but it is an absolute certainty that you won't be getting any more beautiful!" the banker wrote.

"So, in economic terms you are a depreciating asset and I am an earning asset," he said. "Let me explain, you're 25 now and will likely stay pretty hot for the next 5 years, but less so each year. Then the fade begins in earnest. By 35 stick a fork in you!"

"It doesn't make good business sense to "buy you" (which is what you're asking) so I'd rather lease," he said.

While the woman has since removed the ad from Craigslist, it -- along with the response -- has become a popular email joke that, bank JPMorgan Chase says, led to one of its bankers mistakenly being credited with writing the response.

Brian Marchiony, spokesman for JPMorgan Chase, said the banker did not write the response and that his email signature accidentally became attached to the ad and response when he forwarded it to friends and it then wound up on blogs.

Craigslist was not immediately available for comment, but a spokeswoman told The New York Times that "it does look as if the post was made sincerely."