You have to keep in mind that the 945 is a custom shop gun. Were S&W to make it a standard production gun, it would be in the $700 to $800 range. But the scalloping and such are a definite factor in price.
I think these things are a great idea. They've essentially used as many parts as possible from their standard DA .45 autos, substituting a new frame to accomodate the trigger and grip safety. But the mag, slide, barrel, etc are standard S&W, so the out of the box reliability is virtually guaranteed, rather than being the typical 1911 crap shoot.