Be sure to let us know when you find one. I have downloaded a bunch of Hauptwerk free file sets with .wav files and am planning on running them thru Loop Auditioneer this winter to create substitutable stops which can be used to replace stops in the GO Sample Sets. A lot of work - using Audacity and Loop Auditioneer!
FYI - I currently run four organs at the same time using a computer with Quad-Core and 16GB RAM. I load them in multiple LINUX Work Spaces, then pick combinations on each for blending purposes. They are - Burea Church, Wildervank, Skrzatusz Sauer and the Barton Theatre. Makes for wonderful Principal Chorus and fabulous Tutti.