As we didn’t want to wait for professional PCB assembly, we assembled the first batch of 35 OpenPCR boards ourselves. It took some time but came out decently. The biggest difficulty was soldering the H-Bridge IC, which has three large power connections on the bottom of the package, plus fine pins all around it. We managed that by effectively doing reflow soldering with solder paste and a toaster oven, and then soldering the through-hole components afterwards.
The OpenPCR PCB
That's one large Arduino shield
As much fun as that was, I’ll let a pick and place robot do it next time. I’ve been looking at Screaming Circuits for PCB assembly in the ~100 unit range, though please feel free to suggest any other companies in the comments.
Ehh,maybe you could try STG electronics for pcb assembly in the 100unit range. Just a suggestion.-smile-
I know you are already shipping kits, but for future reference. You might try https://www.seeedstudio.com/depot/propagate.php . They are being used by the prolific https://dangerousprototypes.com/ . Seed Studio seems to specialize in open source hardware, which might fit well with your goals.