The scope doesn't really matter, you could piggyback the camera on anything.
The mount is the bit that keeps the camera steady and moves the camera (and telescope) to track the object you are photographing. Without a tracking mount, you can only take pictures of the moon, and 'milky way' pics with a really wide-angle lens with exposures under 30 seconds or so.
Basically the cheapest mount that will work for photography (without giving you more grief than it is worth) is a HEQ5Pro, the recommended one though is the EQ6Pro, and then the step up from that is really the Losmandy G11.
Rough new prices are:
HEQ5Pro $1199
EQ6Pro $1599
G11 $4500 and up to $8000 depending on config.
If you are looking at a 10" scope or larger down the track, then you are looking at the Titan or PME etc. and you are up over $10,000 just for the mount with no end in sight
As for a telescope, an ED80 is a great place to start for photographing the larger and brighter DSO's and would be enough to keep you busy for a couple of years. It is also light enough that you won't be taxing the mount once you add the auto guiders, filters, tetrad, extension tubes etc. etc.
I'd strongly recommend getting at least the EQ6, then when aperture fever hits, you don't have to get a larger mount.
So basically, you will need a mount and a scope to get started, an ED80 and the NEQ6Pro would be a great start. Anything less and I reckon you will end up so frustrated as to drive you mad.