Ideally the miners can be sent to you and I can send you payment. You can verify that the hardware is as promised, collect your fee and release payment / the merchandise.
This puts the escrow in a bind and no way they do this. They touch money not equipment. Maybe one will do this but will only lead to issues especially for hardware. Who's at fault if it's broke upon shipping? Now escrow is out money, doesn't make sense on their end to take a risk