There are no official American saturn wireless controllers. There are the pal release (black) and the japanese release (white). An ebay seller has a single japanese controller;
http://cgi.ebay.com/Sega-Saturn-Wire...item3f03f743f6
Thats although a horribly high price, near the same I paid for a boxed set.
I would strongly advise NOT getting the pal (black) controllers. I have both sets in my collection, and believe me when I say it; the plastic in the receiver that plugs into the system is WEAK. I've also seen quite a few receivers that are broken in this area (although they do sell for cheaper, and if its just one of the prongs, then its just that controller port that doesn't register - you can still use it).
Hunt for the japanese controllers. They feel stronger, AND they also can be programed as a TV remote!!! Although its just earlier tv's that utilized an IR signal from their remotes. If you want I can try and post a scan of the instructions for programing one.