When selecting the right machine speakers for your rig, there are three items to consider: sound quality, additional features, and price.
Sound quality is a shifting objective, but broadly speaking: better sound quality is given by cheaper, less elaborate devices, but the soundscape is not that nuanced, and the volume is often not so loud. More costly, more advanced devices strive to offer richer treble, darker bass, and more important vocals. Among the three facets of tone, a fantastic pair of speakers does not make you choose; it should be balanced.
In more costly speakers, extra characteristics appear to be standard, but even cheaper versions can have them. Discrete bass/treble buttons are the most prevalent extra feature, but you can also provide remote controls, wireless functionality, and RGB lighting. None of these things are strictly important, but they will make it a lot easier for you to live, particularly if you want your machine to become an audio powerhouse.
Ultimately, expense is very self-explanatory. More expensive speakers prefer to use superior materials, much as most gadgets, and therefore deliver better sound. On the other hand, you only pay for beauty over substance sometimes, to make sure that you read feedback wherever possible before committing to a buy.