Sprint GT Compatible Parts List

Does anyone know of a compatible parts list for the Sprint GT? My old Aprillia forum had a list of parts which were compatible between Aprillias and various other makes and models. Sometimes the price difference was huge. I am particularly interested in other brake rotors which are compatible with my Sprint GT. I cannot believe there isn't another bike out there with same dimension rotors, which aren't almost 180 quid a rotor. I just bought a set of massive drilled and vented front disc rotors for my E class for £54 a pair!!! Bike spares do really take the p*ss.