Why do ticket prices vary?
Availability and prices of tickets on the viagogo ticket exchange are driven by market demand; they are not determined by viagogo.
Face value is the expression used to refer to the price printed on the "face" of the ticket, i.e. the price it is sold for on the primary market. This price is determined by the concert tour promoter, the club or organizer of the event.
The face value of a ticket can differ from the selling price, because the tickets on viagogo are sold at "market value". This is the price a consumer is willing to pay for a ticket to a specific event.
If the event is in high demand, the selling price is likely to be higher than the face value on the ticket and vice versa.