Quality manufacturing, especially with audio electronics, is definitely one area where you truly get what you pay for. Sound quality is not about how loud will the volume be. It's more about how will the clarity be at varying volumes. Higher quality, which results in the better sound clarity, always costs more.
Based on the other posts, I am not sure which this question is referring to: Orators at rallies or conferences or the equipment which delivers their speeches, among other things. In either case, there's a certain variation of quality even at that level. Some expensive orators are not worth it, as they're only doing what they do for money and don't always have a point. Some expensive orators, however, know what they're doing and make a living off of giving quality speeches. Reputable orators are always worth the money they demand, unless it accounts for over 50% of your event budget. In that case, it's never worth it just to hear one guy or gal speak for an hour. When it comes to audio equipment, it's sort of along the same spectrum: It depends on your needs. Basic speakers are okay and will get the job done, but the expensive ones will do the same job better. At certain thresholds, you're going to want something that's not going to have any fuzzy static or skips. If you're using that sound system at a big event, pay more for it. If you're a DJ, pay more for your equipment. If the sound system needs to live longer, buy a better one for more. If you have extra money and want a home theater, go for something middle-of-the-road and save a little, as your needs aren't to the same level as a rock concert, traveling DJ, or dinner hall. There really is no middle-of-the-road for orators, and therein lies the key difference between the two. Prestigious orators are worth the extra cost in most circumstances (unless they overcharge, so doing a reputation check is always recommended), as are more expensive sound systems (like with orators, be sure to read the reviews, as a $300 sound system might have better reviews than a $500 one). To put it bluntly for either circumstance, the decision is yes, in most circumstances. Do your research and determine what is most effective for your budget.
I think that expensive speakers are definitely worth it. You get what you pay for and you will see the difference when you spend a couple of extra dollars on speakers. Good things are not cheap, and cheap things are not good. If you spend a little extra you will not be disappointed in the product.
Of course, this question is better answered after the speech than before. If somebody is offering an ex-CEO or ex-President a million dollars for a one hour speech, you can be sure the matter has been researched from an economic point of view. It seems ridiculous for the average person to figure that kind of money for any speech, but be assured, the sponsors have their reasons.
For most people, speaker quality has little to do with the benefit they will experience from listening to a stereo or other sound device. Most speakers provide a fairly decent sound, and even the most economical speakers usually aren't horrible. So unless you are very concerned about sound quality, the quality of speaker really isn't a big deal.