Just saw this while looking for holiday shutdown schedule (which is not posted, but was 12/29 thru 1/3 last year):
Special Offer for 2 Layer Green PCBs November 28, 2013 By Katherine
Due to optimization on production process and reduction on material costs, 2Layer Green PCBs will be offered at special prices from now on.
2Layer Green PCB 5cm x 10cm Max will be sold at $14.9 and 2Layer Green PCB 10cm x 10cm Max will be sold at $19.9. Unless noted otherwise, the prices will remain unchanged in the future.