BMW Repair: Real Wheel Bearings, rear wheel bearings, rear quarter panel

Question
I've got a '93 BMW 325i that's been making some awfully funny noises lately.  It's recurring but seems to go on and off . . . . this time, however, it's staying for the long haul.  The best I can describe it is as a scraping or grinding coming from the right rear passenger side.  I had taken it to my mechanic a number of times, each time he had instructed me that the power steering fluid level was low.  Seemed odd to me since I did not have any difficulty in steering but strangely enough the sound seemed to go away for awhile.  This time when I took it in, he informed me that the issue related to the rear wheel bearings needing to be replaced.  Since this evaluation wasn't caught in my earlier visits, I'm not quite fully comfortable with his assessment.  The car is still making the noise - that is for sure and probably won't go away until it is fixed.  My question relates more to (1) how can I confirm this is the issue that will remove the noise, (2) what are the ramifications if I don't have fixed and (3) what should I expect for replacement parts and time to fix?

Any help/advice you could give me would be most appreciated!

Best regards,

-Mike

Answer
You can't truly be sure until you take apart the bearing and look at the wear.  You could hold your mechanic to his word and ask him to see the worn ones after replacement.  Other possibilities include the drive axle is rubbing or a problem with the pads, it's hard to tell without driving or looking at it.  If you don't fix it it will get worse and worse until  It's undriveable (50,000 mi or more).  The half shaft and or hub may need to be replaced should you wait more than a few thousand miles.  As far as the wheel falling off or locking up it's hard to tell without looking to see how bad it is.  
do this simple test:
go to the back of the car, put your foot on the top of the wheel (on the sidewall of the tire) and push hard till the rear end of the car is osscilateing (or you could push on the rear quarter panel) and listen for a clunking noise or and noticeable vibration in the wheel, this will tell you how bad it is.
I'm not sure what it costs to fix but i can gurantee parts will be cheaper if you buy them online.
I would be weary about bringing your car back to the same mechanic if he figures a rubbing noise in the rear could have anything to do with power steering.  your car is a complex mechanical computer and any unskilled or untrained person touching it will likely cause more damage than they set out to fix so you may want to call around and see what other mechanics have to say before decideing.
-cheers