I recently received the pest & home inspection report and there is faulty grades and the beams supporting floor joists are sagging in between pier blocks with cellulose debris to be removed(major foundation issue), no attic access, door bell didn't work, no ventilation in crawl space, leaking drain line underneath tub, faucet leaks, 2 drawer fronts are broken at bottom of closet, bathroom closet won't latch closed, door in between living room and front porch wouldn't open (I assume this is why the agent had the lock box house key on the back door and used only the back door for showings), most all windows wouldn't open (painted closed during rehab) and missing screens, electrical for entire home was only 100 amps instead of the standard 120/220 or 200/220 (assumed this is why all major appliances were unplugged).

MattI am a licensed modular retailer and investor of wholesale RE.20 Years in the industry.Previous statements are incorrect.A mobile home or manufactured home is a "HUD Label "structure which is designed for affordable living and the financing is somewhat tuffer for the buyer depending on credit.They have a metal frame underneath that is built in the home for transporting it to the site.

I think that wall will have to be dug from the outside and replaced, and the outside pressure from the soil minimized by eliminating water (footer tile) and back filling with gravel. 

All came about AFTER I was trying to sand some residue that stuck to unfinished hardwood underneath. 

The area is known to have bad soil and other homes have been built with piers supporting the foundation.  

Shhhhhhhhh A little secrete from an old timer.........From a bag of water conditioner salt rock place some on top of the soil or within a trench and back fill with earth or pack salt rock granules into 1/2 inch round holes drilled 6" apart through concrete 4" away from foundation footings along area of noted termites entering structure, plug drilled holes afterwords.

@Tristan C.Cost is based on number of piers (which can be, but is not completely determined by square footage), number of beams needing to be replaced, removal of old piers & beams, current height of foundation relative to ground level, soil type, any additional carpentry, how busy the contractor is at the time of the bid, and if the property is vacant or occupied. 

You can't really farm frozen soil so this guy bought and renovated a new rental house each winter, so I helped.

First quote was 6500 with us ripping up the underlayment just so the subfloor could be scrubbed and treated from the top and underneath in the crawl.  

Check that the area is served by a sewer, otherwise you need to have a perk type test to make sure that the soil will support a septic system.You may also want to call the utility servers to ensure that they have capacity.