It depends..
i knew i wanted to image, I piled in and got a EQ mount 6" newt (Tripod)
I found out that i needed a motor to image properly... Gave up on that idea and bought a GOTO EQ6 tripod and new scope. imaging solved, for a cost of $2600.
EPIC LEARNING CURVE!
My recommendation is
Buy the DOB, preferably a collapsible as its easier to transport and setup. Skywatcher make good ones.
If you want to do imaging, start on the planets. you need a Barlow lens, 2x will do.
A webcam and a adapter to connect the webcam to the eyepeice. This is what I have
http://www.morgancomputers.co.uk/sho...SubCategoryID=
Ohh and a laptop of some sort.
Connect it all together, look at a planet and start learning.
The result attached, I did this with my 6" scope on the manual guiding EQ.. You just need to follow the planet for a couple of minutes, taking a video, then you stack it in registax.. Seach on here, there is a good how to for registax.
Once you are happy with imaging the planets and you are sure you want to stay in the game, get a mortgage and go nuts
DSLR, Guidescopes, Computers, Larger scopes, observatories...... it all costs money but is worth it in the end.