Looks to be a 750mhz MIPS developed by Realtek
Pricing from various sources varies between $1.90 and $3.80 for 10k quantities which is still absolutely stunning and justifies a rather urgent push to get hold of the datasheet. More information on pricing shows that the actual price direct from Realtek is $11.
Source code, software and firmware links
Unpacking the firmware from one of the source code links shows that the GPU is a PowerVR SGX 531.