You need to be sure the other unit isn't also infested.

But major issues with plumbing, electrical, missing walls, methlab, massive termite infestation, etc. will. 

Even looking through windows, when that can be done, says nothing about the floor that is uneven and totally termite infested. 

There was a hole in our bathroom wall where wecould see the neighbors bathroom, spiders were crawling all over theplace, and last but not least, the place was infested withcockroaches.

At the same time, there is a termite infestation. 

are you saying that $15k for termite work would be the price on a more-or-less healthy property, and that if there's more substantial termite infestation, that it could very well be substantially more?

There would have had to be massive infestation for rat urine to soak through the ceiling!

I see this as a few stages.BEFORE GOING:So before going, I would use the internet and what's available to you right now to find out as much about the area.Look up the crime infested areas using Trulia, look up the school ratings, look at city level stats like unemployment rate, population growth, property taxes. 

I'm afraid my first thought was "oh, why not just hang a raw steak around your neck and wander through a wolf-infested forest at night?".

The previous owner of this property did not screen tenants and the property got very worn down and infested with roaches and mice.