There's a few dozen on ebay, few dozen more in loot, a few more on car mart, then there's the commercial auctions....??!! Almost spoilt for choice. Try your ad in the sale/want forum of this site. Consider buying a more common barn door and converting it to tailgate.
Hopefully you'll find one soon - Although, sadly the planned GMTV phone in competition, where the prize was new tailgate Vito if you guessed correctly how many more bttt's you're going to post, isn't now going ahead.