It can be any brand that you are able to install drivers for on your driver station PC. (So basically any Name brand or Off Brand)
Particularly, this one is popular as it is high quality at its cost:
http://www.andymark.com/product-p/am-2064.htm
I would avoid buying anything too cheap, as they indeed had to cut corners somewhere to get it down to that price point, and the last thing you want is for your perfectly competition ready robot to not work due to a joystick malfunction. (its happened, and it is NOT fun!)
-Kyle