Remember when the Perth Mint did some official Transformers coins for ROTF and DOTM.... well the Canadian Mint has done some coins that are also legal tender - not that anyone would spend them, particularly since their cost is a lot more than their monetary value.
There are two being produced, which are now on sale - a 25 cent coin with a lenticular image of Gen1 Optimus in both mods, and a 25 dollar coin of pure silver with the face of Gen1 Optimus that has glowing paint on the eyes.
There are 25,000 units of the 25 cent coin at C$35, while there are 3500 units of the 25 dollar coin at C$160.

Only available to North American addresses, so if you want these, you'll need a friend or shipping forwarder.

Images here for when the listings come down later when sold out.