Easy job
GO online many places are selling replacement or patch panels that are made of sheet metal. all you need to do is remove your interior, cut out the sections that are rusted prep and weld the patch panels in and then body fill, glass, ice which ever you want to do then sand smooth primer and paint if you do it your self it should take a few days if you know what your doing if not take it to a body shop and yea it should only cost at the most 2500 to have it all done i just did it on my 92 hatch and it looks brand new and it cost me 1000 or little more because i did most of it my self. and bought my own supplies. But yea that place that told you that much is full of crap.