Forget the west. In my experience there are a lot of legitimate products which you can buy in Shenzhen but not on Taobao. Recently my http://8-food.com/ co-founders and I visited Shenzhen from Kunming (much nicer weather) and found micro SD cards (256MB @ 3.5元 / 0.50USD) and micro SD card readers (0.5元 / 0.07USD). Although these were largely falsely marked as larger cards and intended for immoral mobile shops to dupe unsuspecting peasant customers, in reality they are great for low volume industrial data storage on physically modular components. Far cheaper and faster to integrate than a microcontroller! I would say that in our case, discovering the availability of USB lowball storage and validating this approach architecturally paid for the entire trip.