This beautiful Disney Store Brave Princess Merida Costume is available right now on Amazon 
We have seen this Princess Merida dress in the Disney store and although it is a little pricey at $67.75 (plus $5.99 Shipping) it is a beautiful and luxurious Princess dress which your child will want to wear over and over.
Disney Store Brave Princess Merida Costume Dress
Authentic and exclusive Disney Store costume with reliable quality and durability
Features velure bodice with mesh and sequin accents, Merida cameo with jewel accents and dangling flower, long sleeves with ruffled trim, lace trim, glitter detailing, and four-layer skirt features satin and mesh underskirt and organza overskirt
Coordinates with Brave Merida Hair Piece, Tiara, Shoes and Archery Set, each sold separately
Size Medium 7/8 for girls ages 6-8 years old, 50-67 lbs. and 48-54″ in height
For a Princess Merida costume that is rather more friendly on the budget this Disney Princess Brave Merida Royal Dress
This Princess Merida dress fits Fits sizes 3-6X so there is something available for the smaller Disney Princess!
Princess Merida is of course famous for her archery skills so you may want to accessorize with this Brave Bow And Arrow
A final touch is the Brave Princess Merida Wig
Happy Costume Shopping!