To keep demand high across generations, Disney Studios carefully restrict the supply of some home release classics. They are locked away in the ‘vault’ for 8-10 years before being released for a short unspecified time.
Buy them in this window at normal retail price and you can turn a nice profit when they go off sale for another decade or so.
For example, in 2011 you could buy Beauty and the Beast on Blu-ray 3D for just £24.99. In just a couple of years it was on Amazon for a Importantly, not all Disney releases are subject to the vault and only the true classics will maintain such demand.
Right now there are just 2 titles out of the vault which I would recommend snapping up. They are Bambi Diamond Edition Blu-ray and Cinderella Diamond Edition Blu-ray.