He describes the collection of skinny ties, collegiate jackets, and two-tone sunglasses as his “big sloppy Valentine to Boston.’’ Designer Michael Bastian, who graduated from Babson College in 1987, designed his entire Fall/Winter 2012 line around his memories of Boston from the 1980s. He presented the collection this week at Mercedes Benz Fashion Week. “This is my most personal season to date,’’ the designer said.