PCB Prototyping Manufactures
There are many PCB pools or community batch prototyping manufactures that produce excellent results for around $2-$10 a board. This is really a great option if delivery-time is not a major concern for you.
In our development cycle, however, we tend to have very short time-windows available for the initial PoC type prototyping, so it's not always and option for us - , but it may be the perfect solution for others.
Reference to manufactures: