My buddy is racing Ironman Chattanooga on 9.30 and his rear derailleur on his Di2 is shot. He needs one but since it's a gen1, the LBS can't seem to locate one. The part number is RD-7970, gen1. He would be willing to buy either the rear derailleur or even the entire system if it's reasonably priced. Any help would be greatly appreciated!

I posted it on the classifieds section but also thought this would get some additional attention since more people check the regular forum.