It doesn’t really matter that Margie Leigh’s granddaughter, Laura, got the pink iPod she so desperately wanted last Christmas — at age 4. For the now 5-year-old, pink is out this holiday, and purple is in. Grandma in Kentucky will be buying her granddaughter in Virginia a purple iPod this Christmas for one reason — its color. “I know it sounds crazy,” says Leigh, who is retired, “but that’s what she wants.” In the most economically depressing holiday season in decades, there’s one buzzword — besides cheap — that’s still got game at retail: color.