It's not unusual for Rad to run out of one (or several) model. In fact it's pretty common. If you're serious, get on their "list", and they'll tell you a couple of days prior to the new shipment arriving. I would suggest you have your bike on order within just a couple of MINUTES after that time of arrival, or you may find yourself waiting until the NEXT cycle. I tried ordering again 7 minutes after finishing my order (Rad City regular), and they were gone....
Seems like a strange way of doing business, but it's working for them, so it is what it is.