Well that's about 2 or 3 months of a car payement with many months left to pay... If the car is in good shape I would fix it.....
You are correct.Brake lines rust. At least, they were all rusted on my 99 Civic. Lot of road salt is used here in the winter.
Easy fix: rerun new brake lines next to the old ones. All you need is brake line on a reel, fittings and a flare tool.
Redid mine with a friend last year for under 100$.