As for acoustic guitars, you really want to try the instrument before you buy it, if at all possible. The cheap soprano I started with I bought on the Internet. I paid something like $40 for it (that translates to $32 in countries without VAT). The next one was a Lanikai from a local small shop (due to the impact of "The Mighty Uke" film which has been shown world-wide for some years now you can find ukuleles in surprisingly many places). In that shop the owner had (relatively) cheap Lanikais as well as expensive Lanikai ukes in better woods. After having played them all (that's where it helps to start on the cheap one - I knew how to play one..) I found that the cheap Nato-wood Lanikai sounded better to me than the expensive ones from some more sophisticated wood. It's probably because that Nato laminate can be made real thin, and thus it vibrates well despite being laminate.
Since then I've bought lots of ukuleles (beware of UAS, Ukulele Acquisition Syndrome), some over the net, some in shops. The
single net-shopped one I'm entirely happy with is a Flea (well, almost true - the pocket uke I also bought over the net, but that's a special kind of instrument and I'm happy with it). The Flea's and Fluke's perfect intonation (mostly due to their zero-fret) is by itself enough to make it sound good - it's kind of crystal-clear. These are not the cheapest though, because they're actually made in the USA (almost everything else is made in Asia). You can't go wrong with a Flea or a Fluke from Magicfluke. The soprano models started at $179 the last time I checked (but I added geared tuners, rosewood fretboard (as opposed to the original plastic), longer (concerto) neck, and that adds up quickly).
My best ukulele I found in a shop when I was travelling (I always keep an eye out for shops when I travel because the local selection in my town is limited). The good thing about ukuleles is that it's not a problem bringing one as carry-on baggage on flights, so it's OK to buy one while on travel. I also own solid wood ukes bought over the net, but even if OK it's not the same as one you can test in a shop. Also because what's good for one person can be mediocre for someone else. It also depends on what style you'll prefer to play (fingerstyle, strumming).
So, in short, I wouldn't spend too much money on a ukulele bought over the net.. you would have to be very lucky to get one that you really really like. So it's generally better not to go too high in price (and still avoid the hopeless ones - as I said earlier, if you go really cheap then go for Makala and stay away from everything else). After owning one instrument you'll soon be in a better position to select your next one, although it still holds that you should really try it in a shop. And there will be variations, just as for guitars, so even if you find a good one in a shop it's unlikely that one of the same type bought over the net will sound the same.
And, as MTGuru said - as the price increases you'll get diminishing returns as far as sound is concerned. I would say even more so than for acoustic guitars. Oh, and I support the suggestion of hanging out at ukulele underground for a while. Just beware that nothing can feed a growing UAS as hanging around there, you'll soon get the impression that this and that particular expensive instrument will give forever joy if you can just get your hands on one.. now, where else have I seen something similar?
-Tor
