The original post by oh_the_blood was pretty confusing. When the post first appeared, I almost jumped in to answer the post with a reply to the standard question: "What kind of bass gear might I be able to find in a pawn shop that would get me started on bass?" Then, I realized that he had a particular sound in mind, which is why he was looking at fx pedals and guitar amps and such.
Yes, I'm quite familiar with the sound he is describing. LOTS of people have sought this sort of heavily distorted bass sound, that really sounds more like a distorted baritone guitar than a bass. Not just metal guys, either. Both Chris Squire and John Entwistle have used guitar amps (Marshall's, usually) for the higher frequencies of their bass rig to get a distorted "lead bass" tone.
After thinking about this quite a bit, here are my suggestions for oh_the_blood. First of all, if you choose to use a guitar amp, you'll probably need one that uses a 4x12 to get the low frequencies AND the distortion you're looking for. A better solution (meaning a more flexible way to go - in case you'd also like to have a bass that actually SOUNDS like a regular bass guitar, someday) would be to find a nice bass rig and then stick a distortion device in front of it. Very few bass rigs will provide the amount of distortion that I believe that you are looking for. (I'm not actually familiar with the band that you mentioned.) In fact, the only bass amp that comes to mind that would give this sort of sound WITHOUT a distortion box would be the Mesa Boogie Big Block, and that is only because it has a distortion unit already built in. As for the specific tone you are looking for, you would need to just try out several distortion devices until you find one that gives you what you're looking for. There are the "usual suspects" to consider - the Big Muff Pi,
the ProCo Rat, etc... I would strongly recommend checking out the SansAmp Bass Driver pedal. This is a preamp/floor pedal that will give very good crunchy distortion sounds on bass. It actually sounds pretty good on guitar in certain situations, too. You're not likely to find one in a pawn shop, though. People tend to keep 'em forever when they get one. They are incredibly handy toys to have on hand if you are going to be playing any bass at all. You would have to buy one of these new.
As for basses that you might be able to find in a pawn shop, Fender, Yamaha, and Peavey are all sold in sufficient quantity that you might be able to find a good deal on one in a pawn shop. Any of these should be serviceable. As for bass amps, you will probably run across lots of Ampegs, Fenders, and Gallien Kreugers out there. These should do the job for you. Beyond that, it's just a matter of trying lots of them out, and lots of distortion units, until you find the sound that you're looking for.
Hope this helps.