I think I heard Carmack say that there would be a higher definition version as well, but that it would be (understandably) more expensive.
Yeah, it would be.
It seems they are trying to stay under 1000$.
From a post from PalmerTech (page 41 in the thread on MTBS):
"I hate to succumb to hype, but in an attempt to keep people from being to upset about the delay: Imagine an HMD with a massive field of view and more pixels than 1080p per eye, wireless PC link, built in absolute head and hand/weapon/wand positioning, and native integration with some (if not all) of the major game engines, all for less than $1,000 USD. That can happen in 2013!"