May cheapest PCB service be with open hardwarists!
Not everyday, but we keep negotiating with our PCB fab for better price over their best offer… Now we managed to get special deal for 5cm*5cm designs, and a good one for 4 layers.
Also, there are some adjustment to the details, like you can choose to have 50% e-test only to save a few bucks, diving the cost to 13$ mininal.
For more detail and brief step by step tutorial, please check our new PCB page in forge: http://www.seeedstudio.com/wiki/index.php?title=Opensourcepcb