Infragistics controls
Soon after using Component Art controls, I started testing Infragistics controls. Infragistics packs far more controls in the suite compared to Component Art. They include a ton of ASP.NET controls, Charting controls, and WinForms controls, all for the same $700. In working with the grid control I saw that it was very powerful with lots of settings but was difficult because of their naming conventions. With Component Art it was very easy, the names used for various control attributes made sense. All in all I think the $700 for Component Art was not justified when compared to Infragistics. The word in the market is that Infragistics is more mature and more used among developers. The developer inside me likes Component Art, simply because of it's ease of use, having said that Infragistics is not that hard too use. You would see immediate developer productivity with both tools, as well as AJAX support out of the box. Which one to buy is your choice depending on what you want to accomplish. If you are never going to need the extra controls that Infragistics has, go for Component Art, even though it costs more. Component Art follows the "keep it simple, stupid" mantra to which I would like to say "keep it cheap as well, stupid"