That unbelievably cute 'droid from Star Wars Episode VII: The Force Awakens, is available for purchase. Believe it or not, it works just like the one in the movie — arguably better, given that the one in the movie is more prop & puppetry than robot. But it’s not cheap.
http://www.theverge.com/2015/9/3/9253461/star-wars-bb8-droid-toy-video-price-release-date
Physics of how that Star Wars BB-8 toy works
http://www.wired.com/2015/09/physics-star-wars-bb-8-toy-works/?mbid=nl_9415
Star Wars BB-8 toy torn apart to see how it works
http://www.engadget.com/2015/09/04/star-wars-bb-8-teardown/ / searchkeys /