I bought my clutch kit from a prominent on-line parts source and it was less than that (about $285) - also turned out to be a Sachs. That had the disc, pressure plate, throw-out bearing, and alignment tool (which fit a bit too tight on the clutch splines). I know the guys at our local AAMCO shop and they turned the flywheel for free - I did have them rebuild my trans in the Dodge Diesel truck to the tune of $3K so maybe that was a customer "thank you".

When you have the flywheel turned be sure the shop knows about stepped flywheels. The pressure plate (also called a "clutch cover" in some parts of the country) bolts to a recess in the flywheel and that recess has to be turned down the same amount as the clutch surface or the clutch won't travel properly. Most pressure plates bolt to the same surface as the clutch surface so that's not an issue but it matters on the Benz. BTW - lots of heavy equipment (tractors, etc.) are made like this so if your local machine shop can't handle it go to your farm equipment dealer.

Dan