It seems a bit to good to be true for me
I would first ask the OEM's if this place is an official reseller for them. Most resellers sell on pre-order,get what there customer paid for,ship it out and don't have extra to sell at the exact same price as the OEM,they don't really want big ticket items sitting around on sold. No phone number or address that I can see and only takes Bitcoin. red flags for me Cointerra are sold out until April and the last I checked haven't started delivery for Dec/Jan orders yet so how does he have 10 TerraMiners sitting around,he could have had everything he could get sold on pre-order.
I may be wrong,but do your homework before sending any bitcoin or see if you can pick-up and pay in person.