I was pretty active on Head-Fi at the time and snatched up this deal when someone posted it. I think the HD800 was still $1500 at the time.
Though that is probably not even my greatest "steal", which could be loosely seen at actually stealing. I bought the Fostex TH-900 from a relatively new online vendor, and they accidentally sent me 2 of them. I checked and legally in the US when a merchant sends you something you didn't order, you aren't required to send it back. I held onto it for a bit and that company never contacted me about it and I sold it new in box for $900. I guess they were too disorganized to notice.
I'm not all entirely lucky or wise with money. I bought the Hifiman Edition X on release for $1400 and similar tier headphones like Edition XS are less than $500 now. But I still like them enough for it to be a permanent part of my collection.
All my steals came when you could buy things on Amazon US and ship them to Oz for virtually nothing, and Amazon Australia didn’t exist. They weren’t really steals from a US perspective - just US Amazon prices on things, which were always at least 30% off domestic prices. Now we have a shitty third rate version of Amazon, the brand products on US Amazon either don’t ship or ship at exorbitant prices, and the only ‘bargains’ are chifi- which are in any case still cheaper on Aliexpress. But for a few years, there were good times.