FYI, here is a quote from a couple of Chinese PCB fabs I have used, and I believe it is cheaper than PCB shopper since it is the domestic price. Prices are rounded to $5:
$20 for 2 lyaer PCB, <100mm*100mm.
Only 1 design is allowed to protect prototyping service (i.e. if you want to run a business like OSHPark, Chinese fabs will charge you much more).
PCB shopper do not make/sell any boards, they are just a database to PCB house websites.
The cheapest 2layer 10pcs 100*100mm is $10 ($7 for 50x50mm) at
http://makerstudio.cc with $6 shipping to US.
I've always wondered why some manufacturers don't allow multiple designs. I find this very inconvenient since they want to charge me extra $9 if I want to put an extra adapter on my board.
Who will actually deny the order, the service provider or the fab ( considering that the fab is separate ) ?
Is the service provider / fab not making a profit on prototyping orders ?