Ok.... you will have to piece this together.... but... for INCREDIBLE heavy tone on a budget (and a great clean sound too).... do this:
1. Fender Bassman Head like this
one. Around $275 if you shop. Add another $200 and get a blackface (65'-67') and get a better clean sound.
2. Mesa 2 x 12 Cabinet like this
one. Around $350 if you shop.
3. And either a
Mesa V-Twin Preamp Pedal, or my personal pick... a
Robert Keeley Modded SD-1 Overdrive Pedal. $115.00
Put
Ruby Tubes in your head (and Mesa Pedal if you get that one), and make sure your head has been biased.
Then... prepare to hold on to your shorts! This will knock you over! Plus... if you go the SD-1 route... (which I think sounds best) you are still under $800...... before you buy the tubes!
Frankly, I prefer a 4 x 12 cabinet (I have a Bogner 4 x 12 with 2 x V30's and G12H 30's in an X pattern)... but I was trying to stay under your budget, and the 2 x 12 does still sound really good. I also had my Silverface Bassman modded to blackface specs... but it still sounded incredible in this fashion before the mod. Now it's just mo'better.
I have some really nice amps. But this comibination consistently FLOORS guys that I work with that do heavy music. The low end is absolutely monstorous.... and translates well in the studio... I like the Royer 121 combined with a 421 or 57. The natural overdrive of the bassman cranked up very loud is quite good... but when you turn on the SD-1 for just a small bit of boost..... oh man.... it just get's nuts! I always set this rig up out of sight... so the heavy dudes can't see it.... and I just let them hear it first. This rig beats out my Bogner 101b, Marshall JCM 800, and Dual Rectifer 85% of the time in a blind test! Guys that DON'T like pedals.... LOVE this tone..... and SWEAR it's not a pedal until they see it! (The secret is Robert Keeley completely re-does the pedal and puts a Burr Brown Op Amp in it- it's INCREDIBLY quiet too).
Plus.... turn the thing up to about 5 with nothing in front of it... and you have a clean sound that will make you wanna cry! Get's even CRAZIER if you have an open back cabinet you can hook up to it. I am getting a Bogner 4x10 open back just for that... very soon.