Depends on what you mean by cheap and great sounding and what it's for: speech, music, youtube, movies...? and your taste... Cheap speaker systems (and even many not so cheap ones) tend to over-emphasise lows and highs at the expense of good clear mids.
Logitech speakers do all right for little money: $10s. Don't buy their more expensive stuff though --- anything more than ~$100. They are not great out of the box as they all suffer from a boomy bottom end: trying to sound bigger than they are (almost all PC speaker systems do that, because consumers seem to like that crap). You can tame that with minimal hardware or software tweaks. OK for music and movies, fine for speech, especially if you EQ them right.
Bowers & Wilkins have great sounding bookshelf speakers for $100s. Second hand they can be a real bargain. Per $ they are the best I've found for all kinds of music, speech, and general crisp clear, no-nonsense unembellished sound reproduction.
What do you mean by cheap? <$100 or <$1000?