It was released on Jon Mac App Store and was purchased around 19.99$. This change has brought Apple the option to release updates every year instead of their traditional every two years or so.
As, Apple has released the operating system with the only available only on the Mac App Store. The goal behind the operating system was to create an OS with better management and synchronizing between different Apple products. Mac OS X Mountain Lion 10.8 is the ninth major release of the OS family.