Depending on the resolution... and people would find anything less than 300ppi grainy at this point... there's not much room around each sub-pixel. A pitch of 60-80um is typical and there's not room to do anything like a resistor ladder or fuse with TFT transistors (3um min gate length) in that area.

The cost&size of flash and a TCON to play back a moving image is pretty damn low in 55nm from SMIC though. Less than a buck certainly. OLED and battery will be your dominant costs.