I don't recall that there was any requirement that it actually be good chocolate. They showed toblerone (which is decent but not actually good - don't you live near enough to Giradelli Sq to know <img src="images/graemlins/wink.gif" alt="" /> ) But you could probably get away with using a hersheys dark chocolate bar. I suspect that the active element here is the crushed chocolate beans which means it could probably be done with used coffee grounds. (I'd never waste coffee of any level of quality <img src="images/graemlins/shocked.gif" alt="" />- but after brewing It might be useable for this)