These are the very cheapest ukuleles. The quality tends to not be very high. You may well experience problems with tuning and intonation. Having said that, they are a great way to start. They are particularly good for getting children into making music.
It is possible for you to pick up a bargain occasionally if you have some idea of what you're looking for. eBay sees a lot of people selling ukuleles without really knowing what they've got. That means they might not know who the maker of the ukulele is or may have mis-described it. If you can pick something up that no one else has seen, you could walk away with a real bargain. As I write this, there are two ukuleles on eBay with thirteen hours left that have piqued my interest: a vintage Pennant ukulele (claiming to be from the 20s and 30s) and a J Chalmers Doane distinctive triangular ukulele from the 70s.
You do have to be careful buying ukes in this price range on eBay. Look at the feedback and if it's a seller with less than 98% positive feedback, be wary. For example, I've taken Antoniotsai ukuleles off this page because I've seen so many bad reviews on the net