Alex Klein and Justin Fenty sat in chairs at the head of the line as hundreds of people waited for the annual Great Maine Bike Swap to get rolling Sunday.

The two friends from Portland had arrived at 8 a.m., two hours before the doors were to open, to make sure they were well-positioned in their quest for the perfect two-wheeled vehicle. With 902 bicycles to choose from, they had a lot to consider.

“I am doing the Trek Across Maine and I need a bike to do that,” said Klein, referring to the three-day, 180-mile fundraiser for the American Lung Association that starts June 19.

The swap, now in its 15th year, drew about 2,000 buyers from across the state to the University of Southern Maine’s Sullivan Recreation and Fitness Center in Portland. It is organized by the Bicycle Coalition of Maine, which offers pricing guidance to sellers online and also in person from coalition consultants.

Last year the event grossed about $110,000, said Brian Allenby, the coalition’s communications director. The amount raised Sunday was not immediately available.

The coalition receives a 15 percent commission on the bike sales and the owners pocket the difference. The coalition uses its proceeds to fund programs such as Bikes for New Mainers, which provides free bicycles to low-income immigrants.

About 150 volunteers were on hand Sunday to guide buyers through the process of choosing a bike. Vendors sold coffee, sports equipment and bike supplies.

Despite the crush of buyers that occurs when the sale begins, there are seldom, if ever, any disputes over the bikes, according to a coalition official.

“I have never seen that,” said Liz Hall, the coalition’s event development director.

Kathy Grammer of Scarborough knew exactly what bicycle she wanted and made a beeline for it after the doors opened Sunday.

That’s how she ended up the first in line at the checkout counter with a never-used Cannondale road bike, worth about $1,500, that she snapped up at the bargain price of $650.

“I had guidance” from a friend, said Grammer, referring to Larry Rubinstein, who happens to be board president of the bike coalition. Rubinstein also was serving as a buyer’s consultant at the event, offering advice to those contemplating a purchase.

“My feeling is someone got this bike and put it in a garage for a couple of years,” Rubenstein said of the Cannondale. “There are others here like it.”

Bargain bikes, priced at $50 or less, also drew attention, including from Stewart Zulieve of China.

Zulieve said he is a bike swap regular. This year he hoped to sell two bikes from his collection of 12, and maybe pick up a couple of bargain hybrids.

“I look forward to this every year,” he said.