From all the reports I've had (as I've NOT tried them), the $100 rebuilds seldom last even 40-50kmi and MOST don't last that long. If you are set on going with a "cheap" rebuild and are doing your own labor, you might consider Auto Zone as they have a "forever" warranty. Most MBs go to the junkyard with both original halfshafts still on the car. 300-400kmi is NOT ususual although many fail sooner. I have had only one fail before 200kmi (the CV joint bound up and I replaced it with a used one with almost 250kmi on it and it's going strong 50kmi later). Used half shafts CAN be a very good choice also and good ones can be had for $75 or less. A quality rebuild will cost ALMOST (maybe 75%) of what a new one would cost.

Marshall