Tickets4U acts as an intermediate trader of Straf_Werk tickets which means that the Straf_Werk tickets offered are being resold. Tickets4U prices are therefore based on the principal of supply and demand. This means that prices can differ from the original sales price which is printed on the Straf_Werk ticket.
When availability is limited, Tickets4U generally pays higher purchase costs which results in a higher retail price. However, in some cases it is possible that tickets are sold below cost price.