I've done the rear lines myself three times on the E36s. It's the solid lines that rust, you can buy a set of replacements from the dealer for approx €70. There are four solid lines that split in front of the tank into two long lines, then to a flexible on each side, another short line and finally a flexible before the caliper. If bought from BMW they will be a steel line with fittings like the original and will be cut to length but not shaped.
If you want to get braided lines you can but a direct replacement from Goodridge but these will only replace the flexible hoses.
If you're doing it yourself you need to lower the tank but not drop it, remove rear section of the exhaust and slacken handbrake cables.
A good mechanic would probably do it in three to four hours depending on how many rusted bolts he meets.