When Kobo launched its “luxury” e-reader, the $169.99 Aura HD, last month, I was skeptical that anybody would shell out for it when cheaper models are available. Early sales results, however, suggest that I was wrong: Kobo announced Tuesday, a day before BookExpo America begins in New York, that the month-old Aura now accounts for “up to 27 percent of Kobo devices sold at retail, with more than 50 percent of those customers being new to Kobo.” The company didn’t reveal how many devices it has sold.

In addition, Kobo says its revenue grew by 98 percent in the first quarter of 2013, compared to this time last year. During the quarter , it says it “grew its user base by 2.5 million readers, bringing its total registered users to 14.5 million, with 15 percent of its new user base coming from the U.S.” That last point is important…