$100 or $1000

My '93 Saturn SL1 has corrosion on the brakeline, about midway between
the engine and the rear wheels. The symptom was the brake light coming
on during my commute home (brakes still worked OK), and discovering the
brake fluid reservoir very low, and fluid like material on the corroded
brake line.
Is the replacement of the brakelines an expensive proposition, like $100
or a $1000? I don't think I personally have the skills to do this, and
bleed the lines.
The car has 102,000 miles, and otherwise runs fine, but 15 years in the
rust belt does bad things to most exposed metal, even if the plastic
body looks like new.