Wow!
That must be a really robust house to hold 7 tons of anything in the ceiling.
If he does have a large cache of parts up his stairs (or up some other place), the reason is, likely, that he is just asking too much for them, hence, few sales. If you are still able to communicate with him, you could concede that it appears that you and he will have trouble do any business in the future and hence you will not seek to do so. Then, ask him who will inherit when he goes, so that you can try doing respectable business with him or her.
Of course, once such words are exchanged you would have precluded any future possibility of doing business. (I didn't say it was faultless diplomacy.)
On the issue of knowing if parts bought on U.S. Ebay are good or bad, I had this thought (I hope it doesn't lead to my being overwhelmed but, for now, I can take that chance). Suppose you were to make a purchase on U.S. Ebay with the understanding that you could return the item if not satisfied. As a means of avoiding the costly shipping to AU, you have it shipped to a U.S. forum member (I am semi-volunteering) who looks it over, comments to you, takes detailed photos including specific photos on request. You make a judgement, then the item is either sent to you or returned within the U.S. your risk is the original cost of shipping within the U.S. and, perhaps, you save on charges attached on top of shipping. The original buyer would need to prepay final shipping through the carrier. Sounds complicated and I probabaly haven't thought through all the complications and time involved, but I am willing to try it once or twice to learn if it is, indeed, too much trouble. Maybe no one really needs this, but I thought I'd thow it out there. (Notice I am not suggesting or expecting any fee for this.)
Richard L.