Apple is pushing the starting pricing of the new device, its first with an OLED display, to $999. But new or current Sprint customers who preorder the device and trade in another recent premium smartphone will save $350 off the carrier’s 18-month phone leasing deal.

With AT&T (T), Verizon (VZ) and T-Mobile (TMUS) yet to announce promotional offers on the new iPhone X, Sprint has the best deal on the new phone at the start.

Under the Sprint Flex program, customers who trade in a phone like the iPhone 7 or Samsung Galaxy S7, will pay $22.22 per month for the iPhone X, down from the usual price of $41.67, saving a total of $350. At the end of the lease, of course, customers don’t own the phone. But the flex program allows participants to upgrade to a new iPhone after 12 months, effectively taking out a new 18-month lease. Customers who leave the carrier early would have to pay the outstanding balance, however.

Get Data Sheet, Fortune’s technology newsletter.

Like its initial deal on the new iPhone 8, which went on sale last month, the new Sprint (S) offer isn’t as lucrative as its iPhone deals last year. Sprint and other carriers offered $650 of credit for trade ins last year on the iPhone 7. Sprint did improve its iPhone 8 deal after a week to cover the full cost of an entry-level model, however.

Sprint also said it would offer a “best price” guarantee to customers who buy an iPhone X. If the customer sees the phone sold for a lower price within 14 days of their purchase, Sprint will refund the difference on a Visa prepaid card.

Sales of the iPhone 8 have been slow as many Apple (AAPL) fans await the availability of the iPhone X. In 2017, for the first time, Apple unveiled three new models at once. The iPhone 8 and 8 Plus went on sale in September, but pre-orders for the X model, which is rumored to be in short supply, don’t start under Oct. 27 with deliveries starting Nov. 3.