Hi SDers. Just want to share my experience. Was able to upgrade to an 256 Gb iPhone X with 2 year contract for $699 at apple. Then I bought my phone out (paid off my contract with sprint) for $350. Making my total for the iPhone X $1050 instead of the retail $1150.
I assume this would work for the 64gb model too. It'd be $550 price with 2 year upgrade + $350 fee.
The fee is a flat rate regardless of the phone.
Someone asked for links...
It's apple.com. Select iPhone X. Select sprint. Select two year upgrade.
Link for etf info: