Most likely E-bay or Newegg
Hangover was released on DVD on January 15, 2009.
November 2009.
When it comes out
The Hangover is Estimated for November 2009 DVD release. No official date or announcement yet. I saw on TV it said 12/15/09
Some time in December of 2009
November/December 2011
it already has, but if you missed it, it will soon come out on DVD
This question is subjective. Some of the cheapest DVDs stores are: Rakuten, Amazon DVD, Bargainist, Done Dirt Cheap DVD, eBuyer, Cheapest DVD Price, to name a few.
Toshiba tends to offer the cheapest DVD/VCR combo, starting around $95 new.
December 4, 2009 :)
The cheapest DVD available was "Gridlock" for $3.99 when it was released! Even tough it had a start menu, it would still be the cheapest DVD ever released, from 1996.
Wal-Mart.