eBay offers the refurbished Unlocked Apple iPhone 6 Plus 64GB Smartphone in Space Gray, model no. MG5W2LL/A, for $299.99 with free shipping. That's tied with our mention from Black Friday week as the lowest total price we've seen for an unlocked 64GB model. (It's the best deal today for a refurb by $50.)
No warranty information is provided.