I've been using http://www.pcbway.com recently. They have very low prices and the quality so far is very good.
They are based in China. Usually they need 4-5 days for manufacturing the pcbs and about 20 days to ship to europe. (they can ship with EMS or DHL by request)
One their website you can get an instant quote about the cost of your pcbs depending on the specs you want.
for these specs:
Layers: 2
Substrate: FR4, 1.6mm
Solder Mask Colour: Blue
Silk Screen: White
Copper thickness: 1oz
dimensions: 36X72mm
quantity: 50 pieces
The price was 62$ (including shipping)
check the photos on the attachment.
