The only gamecube type of controller that Nintendo is supposedly producing and is selling in their store is the normal wired controllers for 25 dollars.
And on gonintendo.com I found this article where Nintendo is not planning on restocking wavebirds heres an excerpt of an email from a Nintendo rep from the article:
"I haven’t heard of any plans to offer the WaveBird Wireless Controllers in stores again (I did some checking, and we are still shipping the original Nintendo GameCube Controllers to stores). If you’re unable to find the original Nintendo GameCube Controller locally, you can still order this item from us. - Nintendo customer service rep"
So at this point finding a wavebird itself is a YMMV situation.