Little Star Electronics via eBay offers the refurbished Unlocked Apple iPhone 6s 64GB Smartphone in several colors (Space Grey pictured) for $339.99 with free shipping. That's $25 under our mention from January, the lowest price we've ever seen for an iPhone 6S 64Gb phone, and the best deal for a refurb now by $60. (For further comparison, it's even $80 less than our Black Friday mention of a refurb.)
Note: A 30-day warranty applies but it's unclear who backs it. Also, it's not compatible with AT&T.