Apparently they are very common. You can probably find a real one on ebay or a local coin store. Fakes are available on Aliexpress. I have a real one someplace that I bought when I was in elementary school (probably paid around $1 or so for it).
I remember seeing them at a coin show, but I don’t remember what they cost.
I do have a Roman coin I bought at a show, but it depicts a minor Roman emperor, Postamus, who was killed by his own troops.