I thought Id post an update on this and share what I went through with this guy. Hopefully the information serves someone well later down the track.
Ebay weren't able to do anything about this as the item was outside of their 'protection' timeframe. Obviously they don't control his inventory either and aside from trying to report him to the police, I couldn't get the wheel back.
I used my international shipper who brings back shipping containers. Ebay may not have covered the transaction based on this as I used a third party shipper. However my shipper is organised/trustworthy and also photographs and documents the size weight and tracking number of all the packages which arrive for consolidation. With this evidence I was able to open a paypal case against Mach IV and submit this as proof. They sent a medium sized, 5lb package supposedly containing a rear wheel, and fuel tank. So I knew for sure what was and wasn't in the box given the weight of these items individually weigh more than 5lbs.
When the box arrived, of the 8 items I purchased there were 3 of them. The total purchase cost of everything was well over $1k and theyd sent the items Id purchased for less than $10 combined. The rest of the box was packaging plastic.
I don't know what evidence Mach IV supplied to Paypal, aside from their tracking info showing the package was delivered, and that I used a third party shipper, but thankfully paypal saw reason. I just received my refund this week after 2 months.
So if you do have a purchase go south and are outside of the Ebay return policy, Paypal have a 6 month policy which is what I used. What I check now is all tracking information provided by a seller and look at the weight size information to see if it corresponds with what I purchased (I could have lodged a complaint with ebay sooner had I done this). Fedex and UPS normally list the size and weight of the package sent. I would also check the ebay return policy and confirm if it covers third party shippers. You may not have a leg to stand on if you use one, even if you are in the right. I think Mach IV were counting on this to win them the case. It was what they used to retract my negative feedback with ebay when I asked ebay why it was retracted.
I noticed that the last lot of sandcast parts, their rolled rear rim sold for $810. I also noticed 1 or 2 weeks after that same rear rim was relisted with a $1500 BIN price. Another of their known 'tricks' if they think they can get more for a part, is to send an invoice with a stupidly inflated postage price (they have done this to me and another person I know). Then when you dont pay the invoice, they open up an unpaid item case against you and relist the part for more money. ~edit~ Arnold has confirmed that he legitimately received and returned the wheel I mention here, so the reason it was relisted is legitimate. The tactic I mentioned they have still used in the past.
If people do get burnt, by any seller, then hopefully my experience might help them. Definitely follow up, and report the seller.