what will it cost to repair an ABC System leaking hydraulic fluid on a 2007 600S

At least $3000.

It depends on the type of leak and to the extent to which it is leaking. A pressurized hose on my power steering pump was causing the driver side of my car to droop and that is going to be about $575 to replace ($800 dealership). If it is a strut, count on $1500-$2000 per strut. If it is a line, probably $500-$1000 per line/hose not including labor or fluid. It is a pretty accurate guess of $3000 for a moderately bad leak.