Open Table on Thursday said it is buying Ness Computing, a startup that offers a restaurant recommendation app. The $17. 3 million purchase price of Los Alto-based Ness is worth a net of about $11.3 million when cash the startup has on hand is subtracted. It appears to be a money loser for backers of Ness and CEO Corey Reese, who had raised about $20 million since it was founded in 2009. Its backers include Khosla Ventures, Alsop Louie Partners, Bullpen Capital, TomorrowVentures, SingTel Innov8…