Amazon offers Prime members the Disney Sparkling Princess Cinderella Doll for $5.56 with free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, it adds $6.11.) That's the lowest total price we could find by $7, although we saw it for pennies less two weeks ago. It features a gown and tiara.
Prime orders placed by December 22 are guaranteed to arrive by Christmas.