Cost of foundation repair?

I'm currently considering purchasing a foreclosed home, but it appears the home has some pretty major foundation issues. None of the doors seemed to have trouble opening and shutting, but there's quite a few cracks on the ceilings, walls, and floors throughout the whole house And on one side of the home, in the middle of the outside wall, the brick has separated by about 2 inches all the way up. Also sign on window says possible black mold, i'm guessing due to leaking foundation. But other than that, it's a really nice home. House is 27 years old, 2350 square feet, on a concrete slab, in titus county texas (NE Texas)