Market research firm iSuppli is projecting that NAND flash memory prices will drop to the $1 per gigabyte mark in the fourth quarter, this is after two years of inflated prices that have decelerated the adoption of solid state drives.

The analysts estimate that 1GB of 3-bit per cell (TLC) NAND flash memory will fall to $1.20 during the fourth quarter and possibly down to $1 by the end of the year. This contrasts with prices during 2009 that started at an average of 90 cents per gigabyte and continued to rise until hitting a peak in Q4 at over $2 per gigabyte.

In addition to these estimates, iSuppli says that MLC NAND (2-bit per cell) is expected to see some shortages during the last quarter, which assumingly could pose a halt to the falling prices. On the other hand, there will be sufficient supply of TLC flash memory due in part to the stagnation of capacity needed in SD cards and USB pen drives.

You might recall us touting an aggressive growth of SSD offerings in 2009, but this data makes it obvious why SSD prices have remained almost flat over the last year. Meanwhile, analysts say that in order to compete with standard disk drives, NAND flash memory pricing has to drop to 40 cents by 2012, which would result in a 100GB SSD costing roughly $50. A bullish perspective considering similar drives currently go for at least four times that amount.