BBTS.com (and other dealer sites) usually has them, but are often hefty. But ebay is your best option for getting lucky with a good price, as auctions (and even buy-it-nows) can vary widely depending on the number of people seeing it, the number available at the one time, and other variables.

Or just keep an eye on our own saleyard section, as there are some people offloading the odd BotCon toy in there, including a few from this year.