Mexico’s Cemex, the world’s No. 3 cement maker, fixed on Thursday the prices of previously-announced cash tender offers to buy back a total of $291.6 million in debt due in 2006 and 2009.  The offers are for all $91.6 million outstanding 2006 notes and for all $200 million outstanding 2009 notes.  Cemex said it will pay $1,163.88 and $1,211.10 for each $1,000 of principal of the 2006 and 2009 notes, respectively.  Also, note holders who consent to the buyback before noon New York time on Oct. 4 will receive an additional commission of $5 and $10 for the 2006 and 2009 notes, respectively.  Cemex, which operates in more than 30 nations spanning four continents, said its tender offers will expire on Oct. 14 this year.