score:5
China has three major networks (all of which the government has some stake in, I believe).
China Unicom is the one you'll want to go after as they operate a GSM/3G network that's compatible with most international cell phones, as opposed to the others which mainly use CDMA (much like AT&T and T-Mobile vs. Verizon and Sprint in the US).
As with most questions about prepaid data abroad, this wiki is an amazing resource. Do some more in-depth reading on the page, but basically you can get a data only SIM with 1GB for around $13USD. You can also buy a data pack for a regular SIM.