$50 - $100
In this price range, you'll be able to get a well-made, easy to play ukulele that shouldn't have any big issues. They won't be spectacular, but they should be playable.
In this range, it's possible to pick up a nice used ukulele on eBay with some smart bidding. There are risks involved in this. Buying a second hand ukulele on the net is a bit of a risk. The uke might have problems with cracking or warping.
Check the pictures and description. Obviously, the more thorough and knowledgeable they are, the more you can trust them. On the other hand, you might be lucky enough to stumble upon a bargain before anyone else finds it.
In the $50 - $100 price range, it's worth taking a risk occasionally.