"have barely sold" is correct and usable in written English.
You can use it when referring to something that has only had minimal success in terms of sales. For example, "Despite our efforts, we have barely sold any tickets to the event."
The smartphone business was growing fast, everyone was profitable, and the arriviste iPhone had barely sold a million devices in the previous quarter.
Fifteen years later, though a National Book Award winner, Mr. Bellow was disappointed that his fourth novel, the much admired "Seize the Day," had barely sold 5,000 copies, and was still accepting money from a father who was contemptuous of his literary aspirations.
Majdi Wazwaz, who opened his Holy Sepulcher Antiquities shop a few days before the outbreak of violence in September and has barely sold a thing since, sat on the stoop watching a few Brazilian pilgrims pass briskly by the souvenir stalls.
While Canada had barely sold any sort of military hardware to the world's largest military, things changed in 2013 as Canada right after chastising the communists for being a target of their cyber warfare inked a military-partnership agreement.
Steve also has some disparaging words for Samsung's Galaxy Tab and other competitors, which have barely begun to sell.
Of the other five clubs still receiving parachute payments in the Championship, the uncertainty over Birmingham City's future means they have barely bought anyone despite selling virtually all of their former Premier League players over the past two years, while Burnley, Blackpool, Hull and Bolton have made prudence a priority and only the latter two can still get promoted.
While the Politico Network is three months old, it has barely begun selling ads on newspaper sites.
It is true that encyclopaedias in book form have been wiped out, and that textbooks are fast going electronic; but otherwise the old ways of selling printed words have barely been disrupted.
In a typical year, the recall would have barely ruffled the $22 billion U.S. toy industry, which sells 3 billion units annually.
Real wages have barely increased.
