This year Forgeworld is doing two event only miniatures for the Horus Heresy Weekender, and these were revealed today in their bulletin. Last year was a nice model as well, the Imperial Navigator. I think these ones look nice, but it always saddens me that these will only be available to most of us through ebay. That is the crux though of event only miniatures.
Here is a link to see the latest Forgeworld Bulletin