Amazon offers Prime members the Monster High Monster Scaritage Operetta Doll and Fashion Set, model no. CBX73, for $6.49 with free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, it adds $6.18.) That's the lowest total price we could find by $9. The doll features dimensions of approximately 6" x 3" x 13".
Orders placed via Prime by December 22 are guaranteed to arrive in time for Christmas. (The deadline for standard shipping is December 19.)