Costco has the sprint Iphone X for $480 after bill credits for 24 months. Single unlimited lines are $60 with autopay. If you're in the market for a new Iphone and don't mind staying with a company for 24 months, this is the best Iphone deal for single line owners.
Single unlimited plan on Sprint: $60w/autopay
Iphone X montly: $20
Total Estimate for single line: $90-85