You may find there's a bit of interest from older mk5 140TDI drivers by advertising the brakes on uk-mkivs or somewhere similar. The GTI brakes would be an upgrade for the lower powered TDIs and as a bonus are already painted.
Other than that I would go along, as suggested, the route of keeping them in the shed and putting them back on the car when you sell it as the upgraded brakes you have just put on will always fetch better money and be easier to sell once you sell the car.