Solid Hardwood, Engineered and Laminate Flooring - Concrete Slab Problem

I'm current in the search to buy a new home. I recently went and viewed a home that needed some work but nothing I couldn't handle, well at least I thought I couldn't handle. Then I noticed the floor seemed to be unleveled and the more I looked the more I can see it was very unleveled. The carpet was put down pretty poorly and I was able to pull it back with no problem to take a look at the flooring underneath and can see where someone had tried to repair the floor before. They used the wrong material to try and repair it with (regular concrete with rocks and everything in it). I'm guessing the house settled about 3 inches in some places.

Now my question is how would I go about repairing something like this or would it even be worth the hassle. I've never worked with concrete in this manner and have to say it sounds pretty intimidating.

Also I'm not working with much money and would like to know a round about figure on how much this would cost me.

Thanks

Even when you can see it, it is hard to estimate exact time & materials, for concrete substrate flattening. That is why I always charge time & materials to complete floor prep. If I put a $$$ number on it, it may not take that long and may not take as much material as expected, you as the homeowner, may feel "ripped off" The other side of the coin, and I estimate not enough time and not enough materials, I am going to lose money and with most contractors, corners are going to get cut, to make up for the mis estimate of time and materials. Who looses in both scenerios??