PCB fabrication (outsourcing)

Outsourcing PCB fabrication is to have PCBs professionally produced from the files output by your EDA software.

Advantages
This method might seem more expensive, however in the long term it isn't. Professionally produced PCBs can offer much higher quality, with options such as multiple layers, soldermask, plated through vias and silkscreen. These will make assembly easier and save time that might otherwise be spent on debugging potentially low-quality and unreliable PCBs.

PCB manufacturers
A list of cheaper PCB manufacturers for low volume. Note that a company with the lowest price for one size board won’t have the lowest price for other sizes.
 * DF Robot Very good Quality, up to 4 Layers, very cheap.
 * Dirt Cheap Dirty Boards, intended for dirt cheap prototype boards
 * ITead Studio Very cheap two layer prototype service.
 * OSH Park Based in USA, ship worldwide.
 * PCBYA Very cheap pcb house for prototypes.
 * Screenbond Based in the UK. 1 and 2 layer, low tooling cost and cheap for standard turnrounds.
 * Seeed Studio Cheap two layer prototype service with thickness and surface finish options.