Since I just went through this, I figured someone might benefit from a post.
I successfully had my 1999 2-door's rusted, rear, strut towers repaired. The first estimate I got was ~$6000 as the guy wanted to replace the entire rear of the car with a section from a junkyard. But I ended up paying less than $2000 for both sides elsewhere. (I live around Chicago.) The repairs turned out well, but I cannot recommend this body shop as their sloppy work damaged a few unrelated parts on the car. :-/