I think the prices of the iRex DR1000S (currently $859) will likely come down whenever there are competitive devices. It's in any case not the most expensive e-ink type device, that appears to be going to the Fujtsu FLEPias:
which currently run just over $1000, US, and is just now starting to ship. Of course, those are color and have wireless support, but the screen is more in the iLiad size range (8"), and will take a while to get over to the US. Battery life appears to be better. So we'll see, but it's probably devices like the Fujitsu that will start to eventually put pressure on iRex, whenever the early-adopter premium drops or there's enough supply for discounting.
Probably the 800 pound gorilla in all this, is the Amazon Kindle - Text book edition, rumored to be coming out potentially in time for fall classes. Presumably that would have the bigger screen and .PDF support that the DR1000 series do probably best for now. When you look at the Kindle 2, it really just feels like a kicker on the original device, not something new and all that big a deal, maybe even stop-gap. I wonder if they had an 8 or 9.7" device planned, with a touch screen, but then held it off due to supply or design/software/quality issues. Really has that sort of feel to it. The Sony PRS 700 touch-screen really cut down on readability, that's for sure. If an Amazon product needed the hand-holding of the DR1000s, they would have been lynched. Different user set.