Ok some commentators don't realize why SSD's are so expensive. Instead of platters spinning it use's fast transistors that keep their charge when powered down. These are complicated transistor and take up more space to store the same amount of data that a disk platter would.
The speed difference is that the drive can read the data immediately without having to wait for the drive head to physically position itself and read the data off a disk spinning at 10,000 RPM. Because the data is immediately available, the access times are in the nano seconds vs milliseconds for traditional platter drives. Its literally at least 10x quicker to access your data, and sometimes 100x quicker. No physical drive today is capable of a sustained transfer rate over 60~ MB/s, laws of physics prevents the drive spindle from going any faster. This is why we RAID a bunch of them together to get a higher transfer rate through parallel access. SSD's are again capable of a 10x increase in speed because they are not limited by a physical spinning disk with an arm reading a magnetic charge.
The down size is their limited space and prohibitive cost. They are more expensive to manufacture (vs magnetic spindles) and thus demand a higher premium.
You don't store your regular data on one of these, you store your Operating System, Swap file, and other boot / most load as fast as possible programs. This means your computer boots ultra fast and operates ultra fast. Additional data / programs can be stored on a second traditional disk / RAID array and accessed when needed.