Comment It Depends On Your Profit Margin and features (Score 4, Informative) 192
Currently there are ARM Cortex A8 tablets with 7" LCD's using the $5.00 Allwinner A10 ARM soc on sale for ~120ea.
http://www.youtube.com/watch?v=FCvef9IYX0o
http://tabletrepublic.com/forum/cortex-a8-allwinner-a10/
The actual cost to build them is around $60 ea