i found sega saturn accessories and sega genesis accesories.
there is a stunner gun for the saturn and control pads also
for the genesis there is a arcade stick and controller
maybe you might find a deal on ebay but already these prices on the site are deals i think.
link
saturn stuff
http://bestsku.com/platform.asp?catid=Sega%20Saturn
genesis stuff
http://bestsku.com/platform.asp?catid=Sega%20Genesis