Solid-state drives (SSDs) were once premium storage -- fast, stable, durable and pricey. Now, a steady and dramatic decline in prices indicates that the last adjective may be permanently dropped from the storage medium's descriptors.

Prices for SSDs have fallen as much as 65 percent over the last year from such name-brand makers as Intel, OCZ and Crucial. Last year at this time, a 256 GB SSD might set a buyer back $500 or more. Now the same-size drive goes for less than $200. For some SSD models, the price-per-GB is now as low as about 65 cents.

Floods in Thailand

The reasons behind the steep price drop include lower prices for NAND flash memory chips and for controllers, plus competition among makers.

At the same time that SSDs have plummeted in price, their competitors, spinning hard disk drives, have seen price jumps as much as 50 percent because of floods last year in Thailand, where many of the drives are manufactured. The floods have devastated parts of the country, killing hundreds of people and damaging factories. Most SSD manufacturers are located in Korea and Japan.

Because of the rapid price drops and SSD's features, sales of SSDs have increased substantially, while HDDs have reportedly dropped as much as 40 percent for some models.

An example of the radical price drop is Intel's 240 GB model in its 520 Series, whose price at the NewEgg retailer fell from about $550 at the end of February to just above $300 by March and April. The model uses the SandForce SF-2281 controller, a common component in SSDs, and other SandForce-using SSDs show a similar price trajectory.

For instance, the Corsair Force Series GT 240 GB unit dropped from nearly $500 in September of last year to about $250 now. The OCZ Vertex 3 240 GB demonstrated a similar price decline over roughly the same period.

HDD Sales Drop

Both models use the SandForce controller and resemble the Intel drive, and all three use synchronous NAND. SSDs that employ the less expensive asynchronous NAND, such as the Corsair Force Series 3 240 GB or the OCZ Agility 240 GB, have shown a similar price decline.

SSDs with other controllers have also gotten cheaper, such as the OCZ Octane 128 GB, which uses a Marvell controller and has dropped about 40 percent in the last six months.

For years, analysts have contended that, as great as SSDs were, hard disk drives would remain less expensive per unit of storage. The price difference per GB between HDDs and SSDs in 2005, for instance, was 33 to 1. By 2006, that had dropped to 19 to 1.

Now, with per-GB costs for some SSDs as low as 65 cents, the significant cost differential between the two kinds of storage may permanently become a memory of things past. OCZ Technology, for instance, has said that new kinds of NAND flash memory will continue to drive prices down on their models.

SSDs have also changed their status, moving from luxury items to required components for such new product lines as Intel design-specified Ultrabooks, Apple's new Retina Display MacBook Pro, and the newest MacBook Air.