GMC, out of curosity, why do you want to upgrade or replace the existing foundation?
Here in Texas foundation problems run rampet and jacking and other systems are used all the time.
A local company called RAM JACK charges $450 per jack, labor and material, and requires that a jack be placed every 10 feet around the entire home. The jack is placed on a created concrete footing dug in the earth around the home and then the jack is placed on that footing and just left. The earth is backfilled and your set.
Now, If you need new beams to support the floor joists, then that is something else.
you can do the math on the home jacks, but the beams are extra.
I would think that $30K is pretty high for that small of a home, but who knows, its pretty tough going under there and jacking it up that high to install new beams then lowering the home onto those beams and all. its all labor fees and very little material involved.
Let me know why you think you need a new foundation.