I just had a great visit with my daughter and granddaughter in Washington, DC, where we visited the Air and Space Museum and the Museum of the American Indian, but also visited the Baltimore Costco.
Halloween costumes are in, and, while we didn't see the Frozen characters, we did find this Rapunzel outfit, which made my granddaughter almost as happy. Notice the tiara and gloves.
I don't remember a pirate princess in previous years. I thought the mermaid, Ariel (?) costume was especially cute. Costumes are in three sizes, largest is 4-6. I paid about $15.
In previous years these sold out quickly, so, to get a choice of all sizes and characters, go now.