Groupon offers the refurbished Unlocked Apple iPad Pro 9.7" 128GB WiFi + 4G GSM Tablet in Space Gray, model no. MLQ32LL/A, for $549.99 with free shipping. That's tied with our mention from a week ago as the lowest total price we've seen for this model. (It's also $249 under the best price we could find for a new one.)
Note: A 30-day warranty applies, although it is unclear who backs it.