You're missing out on the opportunity to take advantage of the Character Builder, Monster Builder, Compendium, and magazines. Unless money is prohibitively tight, I can't see a solid reason why a regular 4e player or DM wouldn't want to have access to a subscription.
Yeah, this.
Despite them being really badly coded and designed programs and despite the severe limitations of the compendium search tool, if anything a DDI subscription is incredibly undervalued at just $10 a month.