Front Struts

I recently had my 2000 Jag XK8 into the dealer after hearing a noise coming from underneath the car on the passenger side front tire. Upon diagnosis, the dealer said that there was a worn and damaged right front upper control arm mounting and that a new front subframe and arms had to be installed. The cost for this repair was very expensive. I am trying to get a sense if this is a reasonable diagnosis considering the car has less that 60K miles, has never been in an accident and currently operates fine. I suppose I could have hit a pothole somewhere along the way as I live in the midwest. Consequently, I'd like some input as to 1) whether this sounds like a reasonable diagnosis, 2) What should I expect as a ball park cost to repair (i.E. $500, $1000, $5000 etc.)And 3) If this, in fact, a reasonable diagnosis, is it reasonable to use used parts to mitigate the cost of repairs?