An anonymous Apple Authorized Service Provider told TUAW that iMac channel supply is running peculiarly low, with inventory listed at zero for many models.
"While putting in an order today we stumbled upon both our suppliers have no stock of 21 or 27 inch iMacs," the tipster said. "One picture has an estimated ETA while the other shows all current models at 0 stock. All 4 models look similar to the picture that displays the ETAs."
The source is referring to a pair of screenshots taken from their suppliers' inventory systems, which show almost every iMac model out of stock.
In late August, AppleInsider's pricing guide reflected a similar situation, though the supply constraints were limited to the 27-inch iteration of Apple's all-in-one machine. With Tuesday's report, both 27-inch and 21.5-inch models are seeing stockouts
Analyst Ming Chi-Kuo, who provides consistently accurate foresight of Apple's supply chain, said in July that he expects a new iMac model to see release as soon as September. Further backing up the claims of a product refresh are internal configuration files discovered in Mountain Lion pointing to as-yet-unreleased iMacs.
Most recently, a report claimed Apple's upstream suppliers were shipping next-generation iMacs and a 13-inch MacBook Pro with Retina display ahead of a September or October launch date. It is unclear if Apple will present the two machines at a single event or roll them out separately, however the company is said to be unleashing eight new devices this fall with the first major debut being last week's iPhone 5 announcement.