The legendary northern Iowa ballroom known as Buddy Holly’s last venue is holding its annual Halloween costume bash tonight. Linda Vorce is events coordinator at the Surf Ballroom in Clear Lake, where she says the prizes are plentiful for the ghouls and goblins.Vorce says that top prize of 300-dollars is earned by the costumed competitors, who dress up as all sorts of characters — from late, great rock-and-roll stars to mythical monsters.She says the winners of last year’s costume contest looked like something that crawled right out of the Black Lagoon. She says they were scary and unreal.Tickets can be purchased at the ballroom. The doors open at 8 p-m. The band is the White Sidewalls, playing ’50s and ’60s rock-and-roll.