2002 Vauxhall Astra Manifold

I've been told that my Exhaust Manifold has a blow, which is resulting in loss of power and overall smoothness of running of the vehicle.

I've been told its quite common but Im just wondering the extent of work that is required and a rough estimate of cost.

I am in two minds whether to sell or maintain this car. But I know I won't be able sell at reasonable price due to the car performance.

Please help, many thanks.