iTead or Seeedstudio are both $10 for 10 pieces, up to 5 cm square, or $40 for 50 pieces. If you want to get clever, you could panelize 9 of your designs onto a 10x10 cm board, $25 for 10 pieces. You'd need to cut them apart yourself, but that would give you 90 boards for $25, or $0.28 each. I've only done one board with them, but I was entirely satisfied with the quality and turnaround time. http://www.seeedstudio.com/depot/fusion-pcb-service-2-layers-p-835.html
Even OSHPark will do $1/in^2 with a minimum order of 150 in^2. For your board, that would be $1.56 each. Less than the small-run option with them, but quite a bit more than shipping it off to China.
Edit: That price from seeedstudio isn't exactly comparable to OSHPark, as it doesn't include the ENIG (gold plated) finish on the boards--that adds $16 to the order (and that looks like a flat amount--it doesn't seem to depend on the number or size of the boards ordered). And, of course, they don't have the purple solder mask, though a number of other colors are available.
