You have a roman bronze coin but I cannot say of what emperor because the antique coins are not my speciality. Anyway,not too valuable,perhaps some dollars but it depends on a more precise identification!
I succeeded identifying your bronze coin as one minted by emperor Theodosius I (379AD.-395AD), legend ''DN THEODOSIVS PF AVG, REPARATIO REIPVB''. Mintmark SMA?- Aquileia
I found on the net some possible prices for your coin: it goes more than I believed,between 15 and 25euros. Depends on the right buyer...
So,have I helped you on both your inquiries?!