Why not use a Disney collectible poster as a focal point for a child's room Instead of using something that will depreciate in value, why not invest in a vintage poster or several for that matter. Your child will love the poster for the character, and you will appreciate its value as well.
Posters and prints retain their value based on how well they are preserved. So you may want to consider framing it behind shatter proof or plexi glass. Do not use thumb tacks or tape. Be careful of the edges.
Realize, also, that sunlight, heat, and moisture can affect even protected posters. All of these precautions are worth it when you end up with a rare collectible. Check out eBay for famous Disney posters, including Snow White, Mickey Mouse, and Bambi