Solid-state drives aren’t as expensive as they used to be, bringing them within reach of both the consumer and the more frugal enterprise. As this article by Dong Ngo points out, laptop and desktop SSDs can be had for less than $1 a gigabyte. Considering the performance improvement they can provide (you can find plenty of online reviewers gushing over much faster boot-up times, for example), this is not unreasonable.
SSDs aren’t replacing spinning disk as a storage medium anytime soon, but what they do offer is a considerably faster way to execute I/O operations, while leaving the “slow” storage to bigger, spinning drives. There has been a lot of talk recently of performing more tasks “in memory” but this isn’t always feasible from an economic standpoint. SSDs can provide a happy medium in many cases.