There are some on E-Bay. I have a LED tail light and get them from this guy PlastiqueSTM .
Universal ATV LED Tail Light
http://cgi.ebay.com/ebaymotors/NEW-UNIVERS...sQ5fAccessories
Watch his auctions he does two kinds, one is a buy it now that cost more then a standard open bid wait a few days auction. Can be a 5$ difference. You have choices between 4 color LED lights Blue, Red, Yellow or Green as well as 5 choices for the Case (plastic braquet) to go around the light: Blue, Red, Yellow, Black or White.
*Note, Make sure you can are allowed in your area to have particular color of tail light.
Because the dunes in California you will get a ticket for a blue tail light! Trust me I know! :ermm: