The resellers are all taking a risk, in that they order a part, pay about $330 for it and it takes a couple of weeks to come. Some day -- much later than we would have wished -- Tesla will announce them for sale on the Tesla site for around $200. They may thus lose money on the ones they got. In theory at least. In practice there will be people who don't know about the Tesla availability and probably still pay enough for a profit, and even a loss won't be that much.
People are calling these folks scalpers, but most of them are just putting them up for auction, and it is the buyers who are deciding to bid these prices, either because they want it now-now or just have too much money. I have to say I understand discomfort in giving people a password (even though you can apparently create a 2nd account to do it.)
Now, it seems the business for Harumio would be to give you an adapter for free. You would give them your password. They would buy two adapters with your account. Sell one on ebay, give you the other. They would make good money out of that at today's prices. More than they are making with their service.