Well, squeak, as you can see from the Mediastation furor, the features themselves don't seem to be that difficult to develop. Cost of development of the hardware part of any keyboard is probably reasonable consistent across the board.

The thing that's killing Dom is that he has put very little (comparatively) into the style development and sound set integration. And so, what is a promising platform languishes for the lack of good styles.

Each TOTL arranger from the majors not only has at least as much technical innovation as many workstations - Yamaha debuted SA technology on the T2, NOT the Motif, Roland have a far better VK organ and V-Drum integration than any workstation - but ALSO has to have a couple of HUNDRED killer styles developed for it, obviously not something that comes cheap (or Dom wouldn't have this problem!).....

The software costs may easily account for an arranger's higher price (despite what some marketing twerp will tell you).

Developing really killer styles is nowhere near as easy as it seems (hence the dearth of great user styles) and probably constitutes one of the major costs in developing an arranger. If they were that cheap, you would see the majors releasing (even selling!) loads of new styles all the time. But generally, once a new arranger is launched, you don't see a whole lot of new factory styles for it. Their style team is probably already hard at work making another killer set for the NEXT arranger in the product cycle....