When I look at fare information in Expert Flyer, should the ticket be the very last F booking class (one way) or is it really the lower priced A booking class (but that says round trip so half the cost ?) ? Or is this a ticket which doesn't fall within any of the published classes ? I'm trying to work out how much not a "great deal" this is.

(Apologies if I'm asking any obvious/stupid questions. Thanks in advance.)