If they just have to cut and recrimp then you may get away for $100 or so. If they have to build new hoses from scratch I would expect a minimum of $300 for a main set at the compressor, probably closer to $500.

You can build your own. I bought a used crimper set off fleebay a few years ago for about $90 when I added a parallel flow condenser to my 84SD. New ones are in the range of $150. Then you just need to buy hose fittings online. Probably less than $50 in parts for what you need to do.

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2009 ML320 Bluetec
1985 300CD
1981 300TD

Past Mercedes
1979 300TD
1982 300TD
2000 E320 4Matic Wagon
1998 E430
1984 300SD
1980 300SD