PCB source files and Gerber outputs
I had these manufactured by AllPCB and I'm very happy with the results. The quality has been perfect and their shipping time to the US has been under a week across several orders. If you sign up through this link they credit me some cash that I can use for future projects which helps me out a bit.
If you aren't looking to buy a zillion boards, I may have some ready for US orders in my Tindie store.