As Uncle Turbo says, and I concur, it’s a big and messy job. But you need a detailed beakdown estimate from a good mechanic as to what is involved before going ahead. The $800 or so quoted would not be out of line where I live to do a good job and replace all the bad parts, if, indeed, they need replacing.
I would have the underside inspected, and if the body, especially the jacking points, are totally corroded, I would say goodbye to the car. I have disposed of two cars in the past for this reason.