How much is this coin worth

How do you know it is real? I have some repro roman coins like that. Take it to a coin collector.

You might be reading it wrong.
S. P. Q. R. OPTIMO PRINCIPI (http://www.forumancientcoins.com/numiswiki/view.asp?key=OPTIMO%20PRINCIPI).-- On coins
Of Trajan (http://www.forumancientcoins.com/numiswiki/view.asp?key=Trajan), Hadrian (http://www.forumancientcoins.com/numiswiki/view.asp?key=Hadrian), Antoninus Pius (http://www.forumancientcoins.com/numiswiki/view.asp?key=Antoninus%20Pius), Sept.
Severus, Gallienus (http://www.forumancientcoins.com/numiswiki/view.asp?key=Gallienus), Maximinus (http://www.forumancientcoins.com/numiswiki/view.asp?key=Maximinus) Daza, Alexand.
Tyran. Licinius pater (http://www.forumancientcoins.com/numiswiki/view.asp?key=PATER), and Constantinus Magnus (http://www.forumancientcoins.com/numiswiki/view.asp?key=MAGNVS).