Also you can think about it this way - In addition to "the fear of missing out" (FOMO) that is allowing sellers to mark up the price you are also paying the seller (1) to do all the hassle mentioned elsewhere in this thread to buy from bitmain (2) you are essentially using the seller's money for 1-3 months while it sits in BTC/BCC earning nothing until a batch goes up for sale, then they make the order in the short window before the batch sells out, then they wait for the batch to be produced, and wait for shipping from China.  If they used that money to mine for that 1-3 months they would get some profits in BTC.  Instead that money is tied up in the miner that is sitting in the box, earning nothing, waiting for you to buy it.  They may also offer you tech-support to help get it configured and making money if you are a new miner.  The seller wants you to compensate them for that since they are not mining with the device while waiting for a buyer.

Some of that pricing reflects Dec/Jan when batches would sell out in minutes, you had to wait a long time, and BTC market price was $12000-16000 which was the other thing the seller could have been doing with their money.

I tried buying one in DEC from bitmain.  Coinbase was taking 14 days to convert USD to BTC -- then you had to buy in the batch window on the bitmain site before they sold out.. and you had to wait for the batch to be produced in China and shipped.  If you were too late trying to buy you had to wait another month till next batch.  Many people wanted to start mining without waiting all that time and the Amazon and eBay prices reflected the value of being able to get a unit fast and start mining.