Looking for a micro-controller that has built in wifi

Hello,

I am looking for a preferably arduino comparable module that has wifi built in.

Preferably sub $20.

I don't care too much about how many I/O pins it has as long at I have at least 4.

sub $20.

Hah hah! An Arduino without WiFi is more than $20. I suppose you could try a cheap Chinese import version of a wireless router, and hope you can figure out how to repurpose it.