Make damn sure the clutch is OK. Several hundred pound job to get done if it needs replacing.

Is the excessive cost because of the dual mass flywheel?

Yes, plus the high labour cost due to the complexity of the job. You have to drop the engine and gearbox out of the bottom of the car, or, at least, drop one side and pivot the other.

How easy is it to spot a clutch that may be going? My current car has a very high mileage and is on the original clutch. It has a high biting point, but there is no slipping and I don't notice it revving without acceleration between changes which I do recall from a previous car that needed a new clutch.

Signs that the clutch could be on it's way out include a high biting point, banging noises and/or vibration coming from the engine bay on acceleration/deceleration, clutch slip when accellerating hard from low speed in a high gear. Also, if the dual mass flywheel is starting to fail it will begin to break up, and one of the earliest noticeable effects of this is the starter motor constantly jamming-up, caused by parts of the flywheel falling into the bellhousing.

Do the dual mass flywheels start to make tell tale noises if they are about to fail?

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