Clark went undrafted in 2009, but showed well in workouts and was signed that summer for $50,000 IIRC. He set a saves record for Lexington last season. Like Alaniz, the Astros saw enough in him to 'up the bid' a bit to sign him.
Lee Cruz used to be a White Sox (?) prospect, who was playing Independent ball before he was picked up by the Astros to play for the JetHawks. I don't remember the story on Curtis off the top of my head...