For what it's worth, the Derpy toy that we previously had rumor-tagged (but was still available for purchase anyway) has been confirmed totally factual by USA Today's sideblog Pop Candy. You can find the article here.
We just totally made a toy, didn't we?
Looks like she won't only be at Comic Con either. East Coast bronies should be able to pick one up at the My Little Pony Fair. Prices at both venues are $19.99.