Those are very good points you bring up Omard. Something we'll have to keep in mind during this process. (Well maybe not the loved ones)
I don't know how I could guarantee the quality/content of the rock other than just hoping people trust in my honesty. I think Otty is the only person on this board that knows me personally (don't know whether that's good or bad for him though!)
Our initial thought was to try and keep this as local as possible so part of the deal could be the delivery of the rock and us actually aiding in the set up of the tank. (we're assuming the most interest would be from new hobbyists wanting a cheaper way to set up a tank)
Any other ideas or comments???