The only thing that would make me think it is a fake is the $50 on eBay for a Marc Antony. I have been collecting Roman Denari long or not long off, but I wish I knew how to look at the coin and determine if it was fake. Of course it would have been helpful to post diameter, weight and die axis.
live and learn, there's rule of thumb here..if its too good to be true, it probably is..not always, but mostly..
I agree the OP looks fishy, but I am no expert. I'm pretty price sensitive, so I was very happy with this LEG VII for $13.39 via eBay. Usually ones even this worn go higher (I watch them all the time):
Just a note, the coin is not for sale at $45, that's it's current auction price. If real, and this is not my area, it will hammer much, much higher. If you like it then do your research, come up with a realistic price you are willing to pay, at least a couple hundred dollars, and put in that bid. Almost all the action on ebay comes in the final 20 seconds. P.S. And don't post ebay auction listings you want to bid on, you are sending competition to the coin. You can save the listing's images and post them here without the link to ebay.
There are times when, however necessary, truth hurts. ominus1, with his letter of 2015, has shown one such revelation.