The Energon Pub

Pretty good price as of today, $89.98 USD + free shipping! Apparently they are selling whatever stock they have left of it, no total amounts available listed though. Couldn't find a post for this so I figured I'd add one if people hadn't picked it up and were looking for it. They also have YOTH Supreme Starscream and Platinum TF Prime Ultra Magnus, but I don't think the prices are that great ($99.99 and $49.99 repsectively).

http://www.ebay.com/itm/Transformers-Platinum-Edition-Optimus-Prime-Year-Horse-Figure-/360930597682?pt=US_Action_Figures&hash=item540923db32