While scarce, sites hosting source files GIMP (with estensione ".xcf”), proliferate archives file sorgenti PhotoShop. Aside from PSD Graphics there are several other websites that allow free downloading of files ".psd”. The files are issued free of charge, PhotoShop is indeed no ... very dear. [more]
PhotoShop not can open files ".xcf"GIMP, but fortunately GIMP (being very flexible and also lighter antagonist closed source) you.
Here is a non exhaustive list of sites that allow downloading the graphic file source.