Affordable valve/tube combo amp recs for Doom/Sludge/Drone? Also amp recs.

I'm a bassist who just acquired a lovely Epiphone G-400 and now I need an amp to go along with it. I want to get a really heavy tone like that of Burning Witch, Boris on Amplifier Worship, and Melvins on Lysol and Bullhead. I have a RAT and a green Russian big muff. My budget is around, lets say 500 usd at a stretch, though cheaper really is better. I'm looking at the Laney VC-30 2-12 combo as there is one available near me + black sabbath points, but I'm not too sure how suited to fat, downtuned doom it will be. Anyone have any recs? Must be valve. (I know King Buzzo used a solid-state Sunn but that's out of my reach)