That's still mostly true today for mechanical hard drives as well as SATA III based SSD's but a new class of SSD is becoming affordable to the average consumer - PCIe SSD.
Using the PCI Express channel which has become standard on motherboards over the past decade, the PCIe SSD gains additional bandwidth using the faster interface combined with advances in flash storage and an emerging standard called Non-Volatile Memory Express (NVMe).
These video card looking hard drives are capable of far greater throughput than their SATA counterparts when inserted into a PCI Express v3.0 slot on your motherboard. What used to be out of the budget of a home PC is slowly creeping into feasibility now. The above Intel SSD 750 PCIe 400GB card can be yours for around $389 today. True, that's still almost double the price of a standard 400GB SATA III SSD but it's not exactly pocket shattering. Still, why would you want such a thing if it's double the price Here's the answer in one chart:
You're reading that right, up to 2,900 MB/sec read throughput and 460,000 IOPS and extremely low latency.
If you have a high I/O workload these drives are for you at a relatively small premium over SATA SSDs.
The fact that these cards are the size of a video card and take up a PCIe slot is cause for concern for gaming rigs or workstations running 2 or 3 graphics cards however. Aside from the slot and space it takes up, it's also consuming a portion of the overall PCIe pipe that's normally dedicated to the GPUs. You're going to want the latest Intel chipset on your motherboard that you can get to take advantage of this card and reduce bottlenecks. Today that'e the X99 chipset (Haswell-E) which has 40 PCIe v3.0 lanes. You can get away with the more common Z97 Haswell chipset but you won't be able to maximize the potential of the drives. This will become less of an issue with the upcoming Skylake processors and the x100 chipset which have more lanes and ample bandwidth for PCIe SSDs.
There's still the question of space however, and there is another form factor available for these drives in a more traditional 2.5" disk, the example below from OCZ.
This style drive is more convenient for desktops but requires a port that currently doesn't exist in many motherboards - the SFF-8639 connector. There's little doubt that this port will become standard on high end motherboards in the coming months, but until then there are cheap adapters that plug into an M.2 slot if you're lucky enough to have one of those.
The next wave of speedy storage is here and the technology (mostly) is ready to handle it today. The PCIe SSDs are priced at a point that a DIY PC builder should definitely be considering them for any new builds coming up in the future. I don't personally have one of these yet but my workstation is getting on in years and I'll certainly go this route with a rebuild. For any upcoming datacenter SAN builds I'll be eyeing these up and doing some research as well.