The best retailer to keep an eye on if you haven’t preordered yet, is probably Norman Camera. They have twice had the camera available and in stock. A new shipment is expected soon. Camera Canada may also be at or near the end of their preorder list.
Niether B&H Photo or Adorama has updated me about the length of their preorder lists or when they expect their next shipment.
Both LensRentals.com and LensRentalsCanada.com have the EOS-1D X in stock and available for rent.