For the last few years, SDD prices have been falling steadily, thanks to increased NAND production by multiple companies and the transition to 3D NAND, which offers vastly increased densities for lower cost-per-bit. That trend is expected to take a hit in December, with significant price increases expected for Q4. If you’re planning to buy an SSD for Christmas, in other words, you might want to do so now.

According to DRAMeXchange via CTimes, average contract prices for MLC NAND flash drives are expected to rise by 6-10% , while TLC products are anticipated to rise by 6-9%. MLC, or multi-level cell NAND stores two bits of data per cell, while triple-level cell (TLC) drives can store three bits of data per cell. TLC drives tend to be cheaper than their MLC equivalents for this reason, though the lower cost also comes with some drawbacks. TLC drives generally have a much lower number of program/erase cycles and significantly lower write speeds (there’s a read speed gap as well, but it tends to be much smaller). It should also be noted that the P/E cycle penalty for TLC NAND is really only a problem for traditional planar NAND — Samsung’s 3D TLC NAND can manage more than 20K program-erase cycles, which is actually higher than most planar MLC memory. We explain the difference between 3D and traditional NAND here, but if you’re in the market for a drive, I recommend opting for 3D NAND when possible. If you want more information on how NAND works in general and why SSDs are faster than hard drives, you can find that information here.

“The price gap of 128GB and 256GB SSDs versus 500 GB and 1TB HDDs grew larger than expected in the second half of 2016 due to the sharp rise in SSD prices,” Alan Chen, senior research manager of DRAMeXchange, told CTimes. “Nonetheless, SSD demand in the PC-OEM market is gaining strong momentum as SSDs in general have surpassed HDDs in terms of price to performance. The pace of SSD adoption in both consumer and commercial segments of the notebook market has exceeded DRAMeXchange’s estimation. “Irrespective of the undersupply situation in the NAND Flash market, the SSD adoption rate in the global notebook market is certain to pass 30% this year. Furthermore, this figure is expected to be above 50% sometime within the 2017~2018 period.”

Increased prices mean increased revenue, and Samsung is expected to be the big winner here, with a 20% improvement in 3D NAND shipments in Q4 compared to Q3, while Hynix and Toshiba are expected to eke out smaller gains. Western Digital has begun transitioning to its own 64-layer 3D flash and is mass producing a 48-layer version of the same technology already. For now, Western Digital is focusing more on memory cards, USB drives, and eMMC-compatible hardware for smartphones, tablets, and other mobile products.

The shortages are being driven by increased demand for NAND in the PC market and likely by increasing NAND densities on smartphones and tablets as well. For years, the PC industry has continued to prefer conventional spinning hard drives for most products, with some systems available with hybrid cache drives that combine a small amount of NAND flash with a regular spinning disk. Microsoft’s Surface Studio, for example, uses this option. The crunch is expected to be relatively short term, as demand for PC laptops will cyclically decline after Q4, and more manufacturers will have 3D NAND manufacturing online by this time next year.