Just spoke to the TRU on the Gold Coast, and they mentioned that MP Optimus will be in the next catalogue (not on sale, just promoting it), and was really annoyed that Head Office was only sending them, and most other stores, a small amount that didn't even last a day.
He even recommended that we call up Head Office to (complain) question their wisdom... or to see if the "toxic" unwanted elements of Transformers lately has contaminated retailers' decisions, in that they didn't want to risk having more shelf-warming expensive Transformers costing them money.
Unfortunately, the stores themselves are being hassled by disappointed customers, and missing out on sales, based on the over-conservative decision by Head Office.

I was also told that there might be more arriving to the stores over the next few days... so if you miss out, check again until Wednesday. If no more arrive by then, the next lot won't be until November (if my original source was correct about that shipment).