Paul's point is a good one, especially if you use an instrument stand, a right angle connector is the only way to go. ...I tend to grab cords from Radio Shack ...I have never bought a high end instrument cable. People say that they can hear a difference but the cheap streak in me just won't allow me to pay that much for wire.
First - the right-angle connector is fine on some ukes, but depends where the jack is. They don't always work well on the amp end either - depends on where the jack is in relation to the controls. Never hurts to have one of each. There are small connectors that will turn a straight jack output into an angled one, too. Or buy a short piece of cable that has female input on one end and a male, angled output on the other.
The only problem with this is that connectors are hot spots for interference and signal loss so you may get a murky signal if it's not a good connection. Depends on your environment. With use, commector contacts get looser and the contacts get dirty, too, so they require some minor maintenance. I always look for female connectors that can be unscrewed/opened to get at the metal inside. Sometimes the connecting flange needs to be moved back towards the center to force a more reliable contact. And I like to clean the contacts too, to improve the connection (use 99% isopropyl alcohol for cleaning NOT rubbing alcohol).
Second: the real different between cables is in the shielding. Cheap ones have little to none. You can usually hear a hum through the amp when you use them near other equipment or electronic devices or sometimes near metal like heating vents or rads. A shielded cable produces little or no hum (ditto if you're using a mic, by the way and it applies to USB cables as well).
Higher end cables have jacks that can be taken apart and resoldered if the need arises (and it likely will at some point because cables are moved around so there's often fatigue on the solder joints). Cheap ones you throw out and buy new because the plugs aren't accessible for fixing. Higher end cables are less supple, so are not prone to being bent or damaged if caught in something. On stage or at jams, cables get stepped on a lot. Cheapies don't survive long under the abuse.
Pros use very expensive cables because they're better and last longer. But for home use, if you play around other electronic devices like computers and printers (like I do) buy something that's better than the cheapies, something shielded, but not necessarily the top end. You'll appreciate the improved longevity and the lower hum. Most music stores offer a range and can advise you based on where you play and how often.
Think of the analogy of speakers. Why buy a high-end stereo system and power it through a pair of $50 speakers? If you have a $500-$1,000 uke, and a $200-$500 amp, does it make sense to connect them with a $10 cable?
PS. The longer the cable, the greater the signal loss (especially with passive pickups) and the greater the opportunity for interference. If you're onstage, you might need something longer, but at home, 10-12 feet should be more than ample.