Warby Parker's eyeglass frames look great. But the geek-chic style isn't the only reason the spectacles are so hot right now.

The three-year-old company started by four twentysomething Wharton School students gives away a pair of glasses for every one sold.

Philanthropy is cool with this generation, but there is more to why Warby Parker's annual sales are well over a million dollars.

Warby Parker works because they sell good-looking prescription glasses and sunglasses to people sick of paying iPad prices for eyewear.

"We are trying to radically transform the optical industry by providing beautifully designed and crafted glasses for $95 instead of $500," said Neil Blumenthal, 31, one of the company's four cofounders.

You read correctly: The frames they sell, prescription lenses included, are $95. It usually costs at least $300 for you-would-want-to-be-caught-dead-in-them frames - and that doesn't include lenses.

This month, Warby Parker, now based in New York, turned a yellow school bus into a swank eyeglass showroom and embarked on "The Warby Parker Class Trip," a six-month, nine-city tour that began in New York and will end in February in Los Angeles.

The idea behind the trip is to introduce the Warby Parker brand to funky-frame seekers and give shoppers wary of ordering glasses online a chance to try them before placing cyberspace orders.

The company has 12 retail locations nationally, including a small space dedicated to their wares in Old City's Art in the Age, but the bulk of Warby Parker's sales are generated online. Their website lets shoppers upload their picture and virtually try on frames. The company will even send you five pairs to try and "live with" for five days; the shipping's on them.

The Warby Parker bus pulled in to Philadelphia Thursday and will be parked in town through Sunday. (The bus was closed Monday and Tuesday because of Hurricane Sandy, but is scheduled to reopen Wednesday at Second and Arch Streets.)

The curly-haired, bespectacled Blumenthal, flanked by master's of business administration students from his alma mater, was at the bus Thursday, parked in the heart of University City.

He was excited to be back in Philadelphia, he told me while sitting on a leather couch. In front of him were rows of the brand's signature frames and sunglasses; behind him was a clear view of the University City Urban Outfitters.

"It's been just 21/2 years" since he started the business, "and now I'm on panels with the director of Goldman Sachs and Estée Lauder. It's amazing."

The Warby Parker name comes from two characters in Jack Kerouac's unpublished personal journals - Warby Pepper and Zagg Parker.

Fashionably speaking, the founders - Blumenthal, Dave Gilboa, Jeffrey Raider, and Andrew Hunt - were inspired by Kerouac and the other Beat Generation authors - hence the dog-eared Kerouac, William S. Burroughs, and Allen Ginsberg paperbacks on the bus.

They also dig the studious-yet-rebellious looks once sported by Malcolm X and Patrice Lumumba, the first legally elected prime minister of the Democratic Republic of the Congo.

The look, however, isn't nearly as rebellious as their business style, which scholars call disruptive innovation. The term, coined by Harvard University business professor Clayton Christensen in 1995, refers to companies that open up a new market - in Warby Parker's case, that would be to millennials - in an established industry. Customers eventually demand the new model and it becomes the norm.

It is particularly successful at a time when traditional ways of marketing are shunned by technology-savvy consumers, especially jobless college graduates whose discretionary income is practically nonexistent.

Companies that follow this practice include Republic Bikes (www.republicbikes.com), whose customers can design their own lightweight bicycles, and Uber, which lets commuters hail - and track and pay - cabs using smartphones. In both cases, other companies are now trying to emulate that success.

"Warby Parker created a product that disrupted the price point and the distribution channel," explained Andrew Maxwell, professor of innovation and entrepreneurship at Temple University's Fox School of Business. "Add to that the component of charity work, and you have a disruptive business. They are doing things more-established eyewear brands just can't do."

For example, if Luxottica, the world's largest distributor of eyewear, lowered its prices to less than $100, it would compete with itself, Maxwell said.

Warby Parker might never have become a reality if Gilboa hadn't lost a pair of $700 glasses just as he was about to start a semester at Wharton. Unable to replace them for a while, he talked about it with his friends, and after they stopped stewing, they started designing.

Blumenthal, who had just left his job as director of VisionSpring, a nonprofit that manufactures and designs glasses for people who can't afford them, called his contacts in the eyewear industry and found a way to make environmentally friendly glasses. Warby Parker's glasses are made from recycled acetate; the lenses are cut in America, and assembly is in China.

The four friends invested a little more than $100,000 and produced a collection of 15 styles in four colors. They work with VisionSpring to give the glasses away, and so far, they've donated 250,000 pairs. Warby Parker launched its brand with features in Vogue and GQ magazines and within three weeks, it sold out and had a waiting list of 20,000 people.

Warby Parker raised $13.5 million in a first round of venture capital, and in September, raised an additional $36.8 million. One of their investors is actor Ashton Kutcher. Actresses Amanda Peet, Emmy Rossum, and Sophia Bush also are fans.

This fall, Warby Parker introduced a titanium collection - these cost $150 - and its holiday collection will be available in two weeks. There are plans to open a boutique in New York by 2013.

"When we look around the world, we see billions of people on Earth who don't have glasses," Blumenthal said. "We are trying to change that in a thoughtful way."

It's working.

Contact fashion writer Elizabeth Wellington at 215-854-2704 or ewellington@phillynews.com, or follow on Twitter @ewellingtonphl.