If you have a general understanding of how caliper brakes work and have the necessary tools (can be found here:
http://www.clarks-garage.com/shop-manual/brake-02.htm), you could do them yourself.
Meineke or some other brake shop usually do a good job and cost really isn't that much (especially since brake pads aren't changed often). Most caliper brakes have the same concept so there really shouldn't be anything that they can do wrong or not know about.
I wouldn't recommend going to a Porsche dealer unless you really have money to burn.