With ukuleles, the most expensive ones aren't necessarily the best, but the really cheap ones usually suck big time. The sound is the most important, plus if the screws are good so you can tune your uke. The screws should preferably look like the ones on a guitar, not go all the way through the head. The shape of the uke doesn't really matter.
Mahalo makes several very good ukes (and some really lousy ones, too). If you avoid the cheapest ones and try for instance the 320S model, you could get a very good beginner's instrument for a very reasonable price. Same goes for Brüko and Stagg. Jason makes good ukes, too, but they're a bit more expensive.
Since you're on a limited budget, I'll just mention Eagle, Martin, Ovation, Ukiyo etc. as examples of other good uke makers.
Uke player & owner.