This is a very common scam that was happening on Ebay, Aliexpress etc. at the end of last year, less so now it seems.
What they were doing is claim to have a miner on order on a batch due for delivery very soon but what they really do is order a miner once they have your money. Then its just a game of stalling and excuses.
Basically you end up just paying the guy a huge commission to orde a miner from Bitmain for you on a future batch.