You can now purchase Elite: Dangerous on Steam
Elite: Dangerous is now available on Steam and those who already own the game will be able to add it to their Steam library.
Steps when adding it to the library aren't much different than any other game, but there isn't an option to add it as a Steam game unless it's purchased from the service.
Once the Mac version is released out of beta, Steam users will be able to play along with their PC brethren which will also receive the Mac version automatically.
The game will run you £39.99/$59.99 on Steam and more information can be obtained from the Frontier forums.