2006 Honda Element: Lots of rust, also a crack in drivers side door.

I recently rushed into buying a 2006 Honda Element that I understood needed some work but nothing I felt I couldn’t address on my own. However, after I purchased it, I decided to take the plastic rocker panel trim off too see if there was any rust or if the area underneath had to cleaned out. Answer to that was yes, quite a bit of rust. I know it will be pricey to fix, but I was hoping for some idea of a cost if I provided pictures to someone who knows more than I. Thank you in advance!