auto trans leak
 

I have a 98 boxster with tiptronic.It has 61k on it.When the car was at a friends shop on the lift I noticed some oil leaking from the drivers side in front of the rear tire.It looks like transmission oil.I am concerned as it is a sealed unit with no way to add any.It is a small leak,only wet with a couple of drops.Is this common and how much am i looking at to have it repaired?