$20. Though I bought mine when the Gamecube first came out, and it was like $45.
Both of my controllers are broken now becuase I left them up-side for too long. The analog stick tilts. I bought another one. It's orange.
I also higly recommend picking up one of these controllers for the games that don't need the analog stick.
It's not first party but it plays like it. Import only so it's about $26.