I just contacted Noble Collection to inquire if the Slughorn Hourglass would be available since it appeared on the cover of their most recent catalog. They responded that it would be available in late spring of 2015.
As someone that doesn't receive The Noble Collection catalog, I'd like to see a pic of their replica of this. They don't have it on their site or on their facebook. And a google search didn't pull anything up for a Noble Collection version of the prop.