So prior to ordering a battery or 2 on eBay and ask the vendor when they will ship and received this reply. I find it strange that they refer to the few Mavics that have been shipped as "test products":
We are expecting to ship the Mavic batteries in mid December, with delivery occurring mid to late December. It is our goal to deliver all of our Mavic orders before Christmas. Please understand that currently, DJI has only released the Mavic on a small scale to only a few hundred customers. This is to test the product in the real-world to verify all software and hardware works flawlessly. Also, DJI currently has very limited supplies of the Mavic due to a huge surge in demand for the drone. We are working tirelessly to deliver all of our customer’s orders as soon as possible. We cannot guarantee specific delivery dates at this time, but please remember we are working hard to deliver the Mavic quickly. Also, we guarantee that we’ll refund your payment and cancel your order at any time before shipment upon your request. That way you can save your space in line now, with the option to cancel in the event you decide to purchase something else, or if it doesn’t arrive in time.
We are expecting to ship the Mavic batteries in mid December, with delivery occurring mid to late December. It is our goal to deliver all of our Mavic orders before Christmas. Please understand that currently, DJI has only released the Mavic on a small scale to only a few hundred customers. This is to test the product in the real-world to verify all software and hardware works flawlessly. Also, DJI currently has very limited supplies of the Mavic due to a huge surge in demand for the drone. We are working tirelessly to deliver all of our customer’s orders as soon as possible. We cannot guarantee specific delivery dates at this time, but please remember we are working hard to deliver the Mavic quickly. Also, we guarantee that we’ll refund your payment and cancel your order at any time before shipment upon your request. That way you can save your space in line now, with the option to cancel in the event you decide to purchase something else, or if it doesn’t arrive in time.