First...let's be honest. In the $200 to $250 range you quoted a truly
great uke will be a pretty rare find even in a soprano. That's if we're saying that a really great uke is so good that everybody who plays it goes "wow," which is my threshhold for great. You're not even assured of that with the "k brand" Hawiian ukes - though it's far more likely there. I love Mainlands, have my fifth on the way right now, but I would never say that you are always going to get a "great" uke going that route (very high probability of getting a very good one, though).
That said, you can choose from several very good ukes in your price range. So, in this price range, what's the difference between a good uke and a
very good uke? Typically, attention to detail. You're pretty much looking at "factory" ukes in this price range but the extra attention given after a uke comes off the assembly line can make the difference between good and very good.
First, to be "very good" a uke
must properly intonate on every string at the first few frets. It's the nature of fixed bridges that you probably won't get perfect intonation well up the neck (12th fret territory) but the intonation at the first couple of frets simply has to be perfect. It almost never is on a factory uke and that's why folks like Mim, HMS, Mike, Mike, and Mike
set them up when they sell them.
Second, to be "very good" a uke
must have a
reasonable action. Not necessarily "super low" - some people don't even like "super low" - but it has to be low enough that it doesn't adversely affect intonation at the high end of the fretboard or make barre chords around the fifth fret difficult (most high-fret intonation is not setup related, unless the action is outrageously high).
Third, a "very good" uke
must not buzz on any string for any fretting when strummed properly but fairly vigorously.
Finally, a "very good" uke must have pleasant tone balanced well across the range of the instrument with no wierd resonances at particular frequencies.
Note two things that don't appear on my list above - I've said nothing about volume and nothing about appearance. An instrument that has a pleasant but quiet voice can be amplified...I find pleasant but quiet far more desireable than unpleasant and loud! (think about it) Appearance is purely subjective and one man's beauty is another's...well...not beauty.
I
still am not crazy about the Mainland rope binding but that doesn't stop me from buying them! Even dents, dings, wear, and finish flaws are nothing if the instrument is otherwise "very good" (not that you should
expect those things on a new instrument but they shouldn't stop you from buying a used instrument that is otherwise "very good"). In fact, in your price range you might be able to find a rather rough but good Hawaiian or Martin.