For a gift in the
Roman realm, I would look at
Constantine and the Commerative issues. People know who
Constantine is and the Commorative issues are a celebration of
Rome or
Constantinople. There is a neat coin with a helmeted
head of
Roma on one
side, and the
wolf nursing
Romulus and
Remus on the other.
For
Biblical coins,
widows mites are pretty inexpensive.
You might look for the coin first, and then at the
price. What I mean by that is the coin should have some
eye appeal, (look fairly nice), and for
his interests have some historical appeal. I don't know how locked into $50.00 you are, I go for Greek, which is usually more expensive. Nicer coins (which are usually more expensive) retain their value better, dealers usually want to buy them back, years later. Now, that is not a guarantee, just an observation in human psychology.
Of course, people like to collect the 12 Emperors, but those are more expensive. But, you might find one that is nice enough on the one hand, and inexpensive on the other.
If you buy from Joe, you might ask him to throw in a certificate, the certificate is a nice touch. It gives a background, the same on the tag, but just in a nicer format. He usually charges for them, so understand he does not have to do that.