You've asked a question which, for those of us who are familiar with CodeProject, is kind of like someone living next to a river being asked by a stranger where they can find water :)
But, you've asked in the right place: CodeProject is full of excellent Controls for WinForms and ASP.NET !
Here's one example: a combination TreeView/ListView Control for WinForms by Phillip Piper that has functionality, and design capabilities, that I think compare favorably with expensive third-party controls: [
^].
To me, Philip's article is an example of the best of CodeProject: his article, and its code, first appeared in 2006, and Philip has been updating and supporting the Control ever since !
CodePlex, mentioned by Ranjan.D in a comment on this thread, is also a good place to look for Controls.
Learn to use CodeProject's search engine, and "narrow" your searches by being as specific as possible, and setting the "Rating" parameter so that you find articles that have high user-ratings.
happy hunting :)