the mic is actually the little black nub next to the rear-view mirror post. You can literally stuff the wire into the padded ceiling liner very easily, pull it down the a pillar (there is someone on this site who installed a turbo boost gauge who showed how to remove the post) behind the fusebox in the front dash and to the center console area.
I used these harnesses (around 50 bucks or so):
http://www.quickconnectproducts.com/
Did a google shopping search for the cheapest CK3000 Evo kit (79 bucks at time of posting):
http://www.google.com/products?q=CK3000&btnG=Search+Products
And these instructions to rip apart the dash:
http://techinfo.subaru.com/html/downloadFree.jsp?doc_id=219672
Honestly, if you can hold a screwdriver and are willing to fiddle around for maybe 1-2 hours (at a slow pace), you can do it yourself and save some money. Plus, you will know any damage is caused by you instead of some installer.