Dave's advice is absolutely correct, the 8" dob with the cheshire eyepiece and you are off and running.
Of course you will need a planisphere, red torch, binoculars, chair (don't want a case of dobber's back now do we), warm clothes (remember you are mostly just sitting out there so you get cool on all but the warmest nights), mossie repellant (kinda explains itself), a thermos of coffee/tea/whiskey and a cardboard box to carry it all around in
So factor these into the budget, especially the cardboard box.
Cheers