After years of sluggish — or virtually non-existent — sales at Saxa’s the Prime condominium at 333 West 14th Street, between Eighth and Ninth avenues, a late-summer uptick in sales has left the 10-story, nine-unit condo with only one unit left on the market. Why the sudden surge? “I think price has a lot to do with it,” said Michael Katz, RP Miller’s on-site sales associate. His group kicked off a new sales effort at the development a year ago (note: correction appended). Almost immediately after taking the helm, RP Miller slashed asking figures, and invited carolers to sing outside an open house at the project. Two weeks ago, RP Miller & Associates closed on its eighth unit: a 4,000-square-foot, three-bedroom, three-bathroom penthouse with three balconies and a private roof terrace that sold for $4.1 million, Katz said. Back when sales launched in September 2006, the asking price was $9.5 million. It was reduced to $7.5 million in January this year, and then finally to $5.9 million in July. TRD