PCI Express solid-state drives aren't affordable when viewing them together with all other types of SSDs, but if one were to look only at them, it would be possible to argue that some are actually affordable compared to the rest.
OCZ has introduced a solid-state drive add-in board that meets the short description provided above and is part of the Vector series.
Originally, PCIe SSDs were all about capacity and speed, since they could not boot the OS and could only be used in small numbers, since they relied on the existence of PCI Express slots.
Then, the drives gained the ability to booth the OS, making them viable consumer purchases, in theory.
But they were too expensive, even if the transfer speeds of over 1 GB/s arguably justified the high prices.
Nowadays, PCIe SSDs are still very expensive, but it is no longer impossible to actually make lower-cost ones.
It all comes down to the type of storage chips, the capacity and the controller used, and, by extension, the read and write performance.
The OCZ Vector SSD shown at CES 2013 has a capacity of 256 GB, NAND chips arrayed in RAID 0 mode (a SATA 6 Gbps RAID controller) and an OCZ Indilinx Barefoot 3 controller on each of the two Vector SSD subunits.
The sixteen 25 nm Intel-made MLC NAND Flash chips, coupled with the PCI Express 2.0 x4 interface and 512 MB of DDR3 DRAM cache, lead to a sequential read speed of 926.2 MB/s and a write speed of 881 MB/s.
For those that want further numbers, the 4K-QD64 reads and writes are accomplished at 563 MB/s and 501 MB/s, respectively.
Sadly, OCZ has yet to provide the price of the 256 GB Vector solid-state drive. People thinking of buying an SSD might want to delay until the info comes out, since the price premium over 2.5-inch SATA units might be an acceptable trade for the massive performance benefits.