I'm looking for advice on what .NET user interface components are out there on the market. I have been developing asp.net websites and have mainly been using the Visual studio toolbox build in controls supported by the AjaxcontrolToolkit and the applications have been mainly used inhouse running on our company intranet. But now a new client wants a much more professional looking, commercial web application and they have a budget for some user components for use in the application. Any recommendations where value for money will be realised. Interested in components that will integrate well with ASP.NET 3.5 SP1 or even .NET 4.