The Oculus Rift virtual reality headset is available for purchase from the Oculus website, as of January 2015. The headset comes packaged with a development kit intended for use developing software to work with the Oculus Rift.
Other websites such as Amazon offer reseller listings of the Oculus Rift development kit, which includes the headset. However, the Oculus website states that these kits are not meant for resale as they are not consumer products. As of January 2015, the Oculus website is the sole source of legitimately purchased Oculus Rift headsets and should be used to avoid repackaged knock-off headsets and other scams.