DIY is the way to go with these water pumps. Don't expect original Porsche to last long either.
http://986forum.com/forums/performance-technical-chat/49670-water-pump-way-out.html
Except for the PITA of dealing with coolant, the actual WP change is relatively easy. All bolts except for one can actually be reached with a torque wrench, too.
I invested in the Airlift vacuum system; well worth the bucks IMHO. My compressor is only 4 gallon (they say you need a 10 minimum) and works perfectly. I've heard of others that have even smaller ones and it's worked ok too.