Target offers the Disney Frozen Girls' Anna Nightgown for $8.48 with free shipping. That's $7 under our September mention and the lowest total price we've seen. (It's also a current low by $16.) It's available in size 4 at this price; size 6 costs $9.98.
Amazon offers Prime members the Disney Frozen Girls' Elsa Musical Light-Up Dress for $10.82$10.77 with free shipping. (Non-members can spend $35 to qualify for free shipping; otherwise, it adds $6.36.) That's $3 under our August mention and the lowest total price we've seen. (It's a current price low by $17.) It features motion-activated lights and music and fits sizes from 4 to 6X.