BuySpry via eBay offers the refurbished Unlocked Apple iPhone 8 Plus 256GB GSM Smartphone in Silver or Space Gray for $529.84 with free shipping. That's tied with our mention from two weeks ago as the lowest price we've seen for this phone in any condition. (It's $320 below the best deal we could find for a new unit today.) Note: A 60-day BuySpry warranty applies.
With these companies, it might be easier than you think to negotiate your monthly bill down.