9 Hours 9 Persons 9 Doors (New) for $19.99 (eligible for free super saving shipping) shipped and sold by Amazon. Cheapest I have seen it for in a while.
http://www.amazon.com/9-Hours-Persons-Doors-Nintendo-DS/dp/B003VR5PPY/ref=sr_1_1?ie=UTF8&qid=1353123053&sr=8-1&keywords=9+hours+9+persons+9+doors