Been there. I understand that a $400 jib, if you learn to work around the inherent limitations, will get you that jib shot better than no jib at all will. That cobra crane linked to by the last poster is as good a bet you'll find in a cheap jib. If you can stretch your budget a little bit, you'll find a good jib from Kessler Crane (http://www.kesslercrane.com …gcategory&id=26&Itemid=51) for slightly more cash. The cobra is a nice jib for the price, but the Kessler is a nice jib period. With either you will definitely see some bounce, a lack of remote pan/tilt and focus, possibly some lateral play with the cobra, as well as general ease-of-control that is inferior to a truly professional unit (like the awesome jimmy jib), but if you practice and take your time you can achieve stunning results. The kessler will also serve you well should you decide to invest in some remote units, and can be upgraded to the higher end models with a kit.
You can keep solid focus by stopping down or using a wide lens (24mm, even wide open will keep everything more than a few feet away in focus). A remote follow focus and a monitor will allow you (or ideally an AC) to pull focus during the shot with longer lenses.
Eventually (ASAP) you'll need a monitor so that you can actually see your framing while operating, and you'll be wishing for remote pan/tilt and remote follow focus. But you will get by if you are patient and practice, even with cheap gear.
Stay away from ebay jibs. Proaim and the army of other cheaply made jibs on ebay are not worth the money, and will fight you every step of the way.
If you have one specific project or shot in mind, spend that $400 on an experienced owner/operator. People not at the top of the industry are hurting right now, so you could probably get a great operator with something like the jimmy jib and all the trimmings for a full day for $400 if you really look around. You'll undoubtedly get better results by going that route, but if you're committed to really practicing and taking your time, you can achieve professional results with either that cobra crane or a kessler. It won't be easy, and you might be limited in where/what you can shoot, but it's possible.