When I got my *ist DS, I saw great images from photographers with great lenses, using the same sensor. Those lenses weren't wasted on a mere 6Mp camera. The only problem with those premium lenses is knowing that you can't blame the equipment.
The best way to buy lenses is to have a plan, which you create by knowing something about your photography and your requirements. You'll see some questions here where the OP doesn't know a lot about what type of images they want to create. They just want a "better" lens. All lenses are designed to do something particular. If you start with a task, you can identify a lens for it. If you start with a lens first, you might be forced to operate within the lens's limitations instead of your preferences.
In other words, don't buy a Limited lens because it's a great lens or a great price now and they might disappear or it looks cool on the camera. Buy one because you are pretty sure you need it for images you can't get without it. Sometimes you can't know for sure without actually owning the lens, so you can't be too rigid. You might have to sell a few lenses along the way. The plan is also a learning aid, since you are constantly aware of your lenses and capabilities.
That said, I just went ahead and bought whatever I liked and could afford.