Their campaign (“Save the SciFi!”) raised well over their initial goal of $15,000, and Mr. Kalb and Ms. James soon found their spare bedroom packed with piles of used books, which they would rifle through for stories worth saving. At the time, Mr. Kalb, a lawyer who advises tech start-ups, happened to be looking for office space in which to work and meet clients. Before “Save the SciFi!” he and Ms. James had toyed with the notion of having an office with a storefront, but they weren’t sure what they would sell. By the end of the campaign, it was obvious.

The clientele of the store goes well beyond the cliché of the sci-fi geek.

“Everybody’s into sci-fi,” said Mr. Kalb, noting that customers range from 12-year-old girls looking for books about dragons to lifelong collectors like Gary Levy, 59, who works the cash register on Saturdays.

On one Sunday in October, Roy Miller, 44, a man who has a shaved head and was wearing all black, spent several hours browsing Singularity’s bookshelves. A longtime science fiction devotee, Mr. Miller was thrilled to find old favorites like Michael McCollum’s “Life Probe,” which he had checked out of the library as a teenager and loved. That day he was looking for C. J. Cherryh titles.

That same afternoon, Josh Slater, 34, brought a friend visiting from San Francisco, Lauren M. Taylor, 35. Mr. Slater is a visual artist and a regular at Singularity & Co., and for him the thrill of sci-fi is not just in the stories but in the books’ cover art.