Not only are they expensive, they're only available new through the dealer and often special order from Germany, but you can always check with Phil and team through the Buy Parts link at the top of the page. Check the parts forum and wrecking yard for a good used replacement. In a pinch, you can use the #5 line from a 90-93 300D 2.5, 92-93 300SD or 94-95 S350 and bend to fit.
Get new retaining clips so you don't break more lines -
Sixto
87 300D