Tanga offers the refurbished 4.5-lb. Apple MacBook Pro Intel Core i7 2.4GHz 15.4" Laptop with Retina Display, model no. ME664LL/A, for $899.99 plus $9.99 for shipping. That's the lowest total price we could find by $30. It features an Intel Core i7 2.4GHz quad-core processor, 15.4" 2880x1800 LED-backlit Retina display, 16GB RAM, 256GB SSD, NVIDIA GeForce GT 650M 1GB graphics card, 802.11n wireless, Bluetooth 4.0, two Thunderbolt ports, USB 3.0, HDMI, FaceTime 720p webcam, media card reader, and Mac OS X 10.11 El Capitan.
Note: A 90-day warranty applies but it's unclear who backs it.