Lately, I have seen a fair number of bargain-priced N54 turbos on ebay--such as this one.
http://www.ebay.com/itm/BMW-E60-535X...4ff828&vxp=mtr
Now, I believe that chances are fair that these are turbos that were swapped out due to the known issues with the wastegates.
With our cars, I am pretty sure it is not a matter of if, but when the turbos fail. This being the case, is there any reasonable way to purchase used turbos and remedy the problem? I see this as a viable option to paying thousands for an out-of-warranty turbo replacement.
I have done a fair amount of research, and I have been unable to determine exactly what fails. I know there are companies that sell upgraded actuators, but if the problem was this simple, I don't see why BMW would be swapping turbos, so I have to assume the issue is more involved. The only thing I can come up with is that the pivot joint for the wastegate valve is actually somehow failing. If this is the case, I certainly see where this might be impractical to fix.
I would welcome an input on this.