The official Steam page "DayZ Early Access is your chance to experience DayZ as it evolves throughout its development process. Be aware that our Early Access offer is a representation of our core pillars, and the framework we have created around them. It is a work in progress and therefore contains a variety of bugs. We strongly advise you not to buy and play the game at this stage unless you clearly understand what Early Access means and are interested in participating in the ongoing development cycle.” Hall describes the game as "barebones".,
The Steam Early Access build of Day Z runs $29.99 USD, and naturally includes the final version on release.