User blog:Dengarde/Case Zero: Pricing semi-revealed.

I say "Semi" since it's not completely confirmed.

http://www.andriasang.com/e/blog/2010/07/20/dead_rising_event/

According to this article, Case zero, set to be released about once month before Dead Rising 2, will be priced at 500 Yen for the japanese market. For the U.S., that lies a little over five dollars, so the english cost will possibly be $5 or $10, (400 or 800 Microsoft Points).

Also: The game will work as any other arcade title. It will serve as the demo for Dead Rising 2, meaning you can play a portion of the game for free. However, you must pay to get the game in it entirety. It is unknown whether or not that means Case Zero's achivements will be locked until purchase, or if you can get them right away.