If you're looking to get a really cheap ukulele, there are a few reasonable ukuleles around for less than $30. One such ukulele is the Rogue ukulele (which includes a bag, pitch pipes and chord chart for under thirty dollars).

Another good choice of ukulele in the ultra-cheap price bracket is the Mahalo. With them being cheaply made, the quality of them is a little variable. I have two Mahalos, one is great one is awful.

Here are a few Mahalo ukuleles currently for sale on eBay:

Mahalo Soprano Uke Ukulele Ukelele Blue NEW    US $24.30

Mahalo Soprano Uke Ukulele Ukelele Blue NEW    US $32.30

NEW MAHALO UG 30BU PAINTED UKE GUITAR W BLUE GIG BAG    US $11.33

Whenever you spend this little on a ukulele, you're taking a chance. If you can afford it, go for a slightly more expensive but more reliable ukulele such as the Lanikai LU-21.