After investing a fair bunch in scope hardware and observatory, I decided to go a little modestly in the camera dep't and got a Canon 1000d. $699 for the body but I got it with the twin lens kit for $830 at JB. I thought the lenses would be good if I wanted to do happy snaps as well.
For an extra $200 or so, the 450d is probably a better buy for astro, though. Although a dedicated cooled CCD imager may be better for some.
My thoughts on the astro side of things were that I would get started with a colour DSLR that had Liveview, then later I could give it to my kids and upgrade to modded mono 450D with filters etc, after I see if I have any talent and long term interest in this aspect of the hobby.
I placed a great deal on the Liveview function and have now bolted the camera directly to the back of the C8 and and can look, focus and drive it from the PC in my observatory. I don't need diagonals, flip mirrors, anything. I like this function very much.
Later If I go mono, again, I can just bolt the filters etc directly to the scope. Well, at least that's the plan....
