Amazon launching early - and expensive - is a splendid marketing move. Not only have they beat Apple (the other traditionally expensive hardware vendor) in 2009, but they are well in time for textbook adoption for fall classes. Plus the DX will be out & well tested by the Christmas season.
And the hideously expensive price will help lock customers into their market. For most people, after dropping $500 plus accessories for a large-screened PDF reader, even if some other vendor launches a reader with more features or better screen -- whatever -- they aren't going to be as willing to adopt new hardware. Rather they will wait for Amazon to improve the firmware on their existing DX. This is a sizeable investment for this economic climate.
