Starter motors are peanuts on ebay (about 70 pounds IIRC) and are a doddle to fit on the 1.8 Diesel. Just jack the front of the car up and secure it (or put it on a ramp), remove plastic undertray and presto - you've got access. Should only be 3 bolts and a few cables.

Don't forget to disconnect the battery beforehand, though.

Also, reading your initial post again, that "screech" sound could be your starter motor failing to disengage smoothly. Also a hint that it might not be the freshest unit anymore...