Online retailers: Many online retailers sell Katy Perry costumes for kids, including Amazon, Walmart, and Target. You can find a wide variety of costumes, from simple dresses to more elaborate outfits inspired by Katy Perry's music videos and stage performances.
Costume stores: Physical costume stores may also carry kid Katy Perry costumes. You can find these stores in most major cities and shopping malls.
Thrift stores and consignment shops: You may be able to find Katy Perry costumes at thrift stores and consignment shops. These stores often sell gently used costumes at a fraction of the original retail price.
DIY: If you're feeling creative, you can also make your own kid Katy Perry costume. You can find tutorials and inspiration online, or you can simply put together a costume using pieces from your child's closet.