being an eBay seller, I know all about things like this happening. As other people have said, it is a little harsh that you have called the guy a thief as it is something a bit out of his control. As a seller who is the middle man in an operation though (i.e. he sourced the part then handed it over to you) he should have had the common sense to open it up, check that the item in question was of the standard he led you to believe, then re-packaged it properly as to avoid any damage occurring. Now as we don't know when it was damaged (being that it could have been on the trip from japan to aus, or from the seller to your house) it's a bit hard to chase up a shipping company for compensation. Although, I would talk to the seller nicely and civilised and ask him to inform the shipping company of what happened, and see what options they offer in terms of getting your money back.
Now what you shouldn't have done, is got angry with the seller and/or threatened to report him or take action. This will only make the matter worse as he will be feeling that you can shove it because you're blaming him completely; in other wods he won't want to help you at all. Another thing I highly reccommend for next time, is that you ask the seller to ship the item with shipping and handling insurance. That way, if the item is damaged in transit as it obviously was (being that it looked fine in the photo) it is the responsiblility of the shipping company to compensate for both of your losses.
Work together with the seller and see what you can come up with. Due to it being a 2nd hand item he is also in no way responsible for the items condition prior to it being in his control (but the gumby kinda should have checked it when it arrived lol) If the shipping company refuse to pay out your losses (which I think they might) due to having no insurance in transit, then as much as I hate to sound like a douche, you're just going to have to accept what the seller can offer you and move on. Many situations like this are learned the hard way which is unfortunate, but there's blame on all three parties here IMHO.
Hope it works out well for you in the end dude, coz that's a real pain in the arse when your hard earned cash is involved