Cheap, fun, and easy. I'm all about all three of those. If you are too, and I know you are, then have I got the thing for you! Sketchy details here:
And then, after you've followed my sage advice and got a ukulele, hit this link to hear from a guy with actual knowledge and ability and such. He addresses everything from tuning to playing. By the way, he calls it an ooo-kulele. This is the correct pronunciation. I'm just not comfortable saying it yet. Much like SOW-na, and Regina, Saskatchewan. Also note: his hat choice adds whimsy to an already whimsical undertaking. You'll have to define your own boundaries in that regard.