Brakes

The steel lines will be relatively inexpensive, typically less than two bucks per foot but the labor will be the biggest cost. To replace the lines in their original locations on a GM car is not practical because the body would have to be lifted off the frame. Your mechanic will likely leave the old lines in place and just run new ones where it is most convenient but they must be well anchored to prevent flexing and vibrating which will lead to them cracking over time, and hot exhaust pipes must be avoided. Often what the steel lines connect to are rusty and impossible to reuse so other parts might be needed. One word of warning that I wish every service writer or mechanic would give is that you might need a new master cylinder. There's a 50 / 50 chance it was damaged when you pushed the brake pedal all the way to the floor. Knowing that ahead of time prepares you rather than having them run up to you later telling you that more parts are needed. Regardless what it takes to put the brakes back in proper working condition, I would rather see you spend the money on your car than on buying a newer one. I've replaced almost every steel line and the master cylinder on my '88 Grand Caravan because that van has been infinitely more reliable than my newer cars. Look around these forums and you'll see how many expensive problems people are having with all of the silly, unnecessary, complicated computers. You and I don't have to worry about any of that nonsense.

Do you see where the fluid is leaking from, I know you said lines, but has it been confirmed? Lines are a bit of a gray area, you are not going to get replacement lines that are bent precisely for your vehicle. What you are going to get is straight sections of line that have to be formed and routed, or a roll of bulk line that is going to have to be formed, routed, and flared with ends put on. This will probably come at a straight time charge, with the parts involved being relatively minimal <$100. It is all going to depend on what has to be removed for access, and how much bending and forming has to be implemented. If you are not sure it is a line, look at some of the components like the wheel cylinders at the rear, flexible brake hoses, and the master cylinder or ABS hydraulic control unit if this has the Teves system. A note of mention, if it is the hydraulic control unit, these units are expensive($1500-$2000 reman)