With its comic-book set and toy-piano background music, Auctioning the Ainsleys, the new production at TheatreWorks, creates a mood of absurdist unreality before the first words come out of the first character’s mouth. The fast-paced comic drama by Laura Schellhardt (directed by Meredith McDonough) opens with second-generation auctioneer Avery Ainsley (Heidi Kettenring) selling the last possessions of her domineering mentor father—a Stetson hat, a man’s coat and a pair of size-10 shoes.