Hell, you're lucky if BMW changes your oil and rotates your tires for
much less than $1000...

No. My only question is how he knows its the driveshaft and not just the
center bearing.
Are you sure he is doing all of this for $80/ If so that is a good price. A
rebuilt driveshaft I think
is about $400.

After careful thought and consideration Michael Anthony typed:

Sounds like you are being ripped of.  I had a problem with a heater matrix.
The garage would charge ?200 for a new heater matrix, but would only charge
for 1.5 hours labour.  I asked somebody else and they said to change the
heater matrix, is approx 4 - 5 hours, as you have to remove the dash to get
to it (my previous car, was not a BMW).

Took it to another garage, and he said that somebody had been at the heater
martix input pipe (accessable from under the hood) with a pair of pliers,
thus lossening the hose attachemnt and casuing the leak.

The reason why they charge a very small amount of labour, is because they
try to make out they are doing you a favour.  So you will go ahead with the
work. In my case he would havecharged for a heater matrix, which he would
not have replaced, and around ?60 for labour.  Thus making ?260 to
straighten a pipe, that he bent to start with.  All in all 2 mins work, and
he get ?260.

Since them l am always weary of "small" labour costs.  Vest thing to do is
get a second opinion - however dont tell the second garage about the first
garage.  Let him work it out himself.  It will give you more peace of mind.