Some are. Some aren't.
See my post 84.
Late 3rd Century coins are very cheap. Earlier 3rd Century coins are a little more expensive, and much nicer looking, but still very cheap.
This particular one is priceless simply because of its historical rarity.
Go to eBay and type in "Antoninianus" into Search.
This Gordian III Antoninianus is nice.......And still cheap.
Thanks for the info.