NEW YORK (CNN/Money) - ATA Airlines is getting set to go where few of the low-fare carriers have tried to go before: into wider business class seats.

The nation's No. 2 discount carrier (behind Southwest Airlines) is going to start installing a dozen business class seats, starting in August. The conversion of the fleet should be completed by November.

"We certainly elevate the brand with this," said John Happ, senior vice president at ATA. "There's a relatively untapped market out there for customers who want to fly up front but aren't authorized by their travel managers to have a business class seat. Our seats might be $249."

The price mark-up over the coach fares on the same flight is going to be less than $200 and could be as little as $40.

Happ said the airline can afford to give up some seats, even for a relatively small premium, because of the relatively large capacity of its aircraft. ATA flies the Boeing 737-800 as well as the 757-200 and -300. That gives them an average capacity of 200, about 50 or 60 seats more than some other airlines.

"If we had 140 seats instead of 200, it would be tougher to make it work," said Happ.

So far the only other major discounter with a business class is AirTran Airways, which flies much smaller planes -- the Boeing 717 which holds 117 including the 12 business class seats. But because the 717 is five seats across the cabin, adding three rows of business class seats only gives up three seats rather than the 15 seat reduction on the ATA aircraft.

"It attracts customers we might not get if we didn't have it," said AirTran spokeswoman Judy Graham-Weaver. The mix of customers between business and leisure travelers appears to be the same in the airline's business class as it is in the coach seats, she said.

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Graham-Weaver added that some of the business travelers are paying the $35 upgrade themselves when their corporate travel department won't approve even the inexpensive business class seat. AirTran charges a larger premium on some of its West Coast flights.

AirTran is about to start accepting its first deliveries of the larger 737-700 jets in June, and they'll be coming with the business class seats as well.

The other discount airlines apparently won't be following ATA and AirTran into business class seating, however.

"It would impact our business model and increase complexity," said Todd Burke, spokesman for JetBlue Airways, which cites its simplified fare structure as a selling point. "We think that by having fares never higher than $299, that's something a traditional businessperson would find attractive."

JetBlue actually has slight more legroom -- about two inches -- in the back two-thirds of its planes. JetBlue decided to take a row out to give more room, Burke said, but that the location of the emergency exit rows prevents the extra space from being allocated to the seats in the plane's first 11 rows.