Early this month, Toshiba has announced 256 Gb three-dimensional Stacked NAND flash memory chips using a technology called 48-layer BiCS FLASH, which will be available in samples from the month of September 2015. The high-capacity NAND flash uses 3-bit-per-cell (triple-level cell, TLC) technology.
If you're looking for alternate supplier for buying this most dense NAND flash memory in the market, you have now the equivalent 256Gb 48-Layer 3-Bit MLC 3D V-NAND available from Samsung which has already started volume production, as per some of the reports.
V-NAND flash technology is the fastest and densest and also low power consuming NAND flash now in the market. Well that is the case if you stick on to Flash memory. A better alternative nonvolatile memory exactly doing what NAND flash is doing in your system, which is 10 times denser and 1000 times faster than NAND Flash memory is also now available in samples from the joint development effort of Intel and Micron. Intel and Micron jointly developed NAND Flash memory replacing (and also DRAM to some extent) memory devices called 3D Xpoint memory chip of capacity 128 Gb, which is available in sample quantities.
We would suggest you to explore all these three memory semiconductor vendors, so that you have either performance advantage or cost advantage or maybe both.
It's not going to be too late before the electron trapping Flash memory technology replaced by material property changing nonvolatile memory such as resistive RAM (ReRAM/RRAM), Phase change memory (PCM) and also MRAM.