Saw this posted in the ThunderSky group on Yahoo!Groups. Someone tested 38120 sized Lithium Iron Phosphate (LiFePO4) cells from 'Headway', a maker in China. http://headway-cn.en.alibaba.com/
...At a touch over US$0.50 per watt hour, the 38120L are some of the cheapest LiFePO4s I've come across.
... Comparing 3C results with those from previous tests, cell heating was relatively high and it seems to me that their peak power is well short of the best 26650s and 18650s.