The 256M NAND option for Mini/Micro2440 has been discontinued. A memory options actually requires stocking of complete boards with diferent nenory soldered in during manufacturing. The 256MByte NAND chips have ben bypassed by the industry in favor of the 1GByte NAND chips.
If you need OEM quantities and the 128M NAND is too small and the price increase to 1GByte is too great, you can contact us about availability.