Had this very problem with my 964 earlier this year and went through the same thought process- shall I do it myself or whipout the cheque book. The pipe that needed replacing was the one that goes from the oil filter housing round the arch to the botom of the oil tank, and after a bit of prodding around it just seemed to me to have the makings of a completly horrible job. I chickened out and gave it to my local garage. And I was right - it looked straight forward but everything was rusted solid and it turned out to be a right swine of a job. Result was: one very, very fed up mechanic, one big cheque (£400+) and a beautiful braided stainless steel replacement pipe.
Good luck!