Sorry for the delayed reply- am answering remotely from the Louisville Open house!
Just spoke to Zinger's product manager and he says that the Z218TD has been discontinued and is available through dealer stock only.
He unfortunately didn't specify why the floor plan was discontinued. However, it is really good to hear that you guys have been enjoying yours. Should you ever take any fun family pictures with your unit, we would love to use them on the CrossRoads facebook!
Hope this helps,