While it's not quite Black Friday, at the beginning of the book, Therese is overrun by a rush of women wanting to buy dolls for Christmas.
The customers of Frederick's are picky, forcing Therese to hunt for the exact doll they want, whether it has hair that grows or it pees itself. It's a lot like dating: Therese tells us, "If people came for a doll, they didn't want anything else" (1.43).
Carol comes shopping for a doll, and it turns out she does want something else: Therese. But she treats Therese as a doll instead of as a person for a long time. "You're a very pretty girl" (4.29), Carol says to her, and Therese thinks at that moment, "She might have been speaking of a doll" (4.30).
The doll imagery is dropped about halfway through the book, as Carol starts to see Therese as a real person instead of a plaything. But there is one unsettling image late in the novel, when the detective appears and his eyes are "like a doll's blank and steady eyes" (19.35). Perhaps Carol and Therese are starting to see how creepy dolls are. They're like Therese's mock sets: imitations of real things. And instead of dolls, Carol realizes she needs real people in her life.