In Spain, Italy, Switzerland, and England, a quality 5G phone is for sale this week at about US$400 less than the others. The Xiaomi Mix 3 5G uses the same Qualcomm 855 and modem as most others do except Huawei. It features a 6.39 inch full screen with a camera that slides out. The screen is an OLED with 2340x1080 pixels. It benchmarks well against other top of the line phones. The main difference in the much more expensive phones is better cameras.
Huawei's Mate 20 5G should have a similar price when it goes on sale after the U.S. delay.
In the U.S., the 5G choices are an expensive Samsung Galaxy and LG V50, probably less expensive. The LG list for over US$1,000 but is selling for much less. The Koreans carriers are apparently offering a 40%-50% subsidy, some of which may be a disguised price cut.
The difference in parts cost (BOM) between 4G & 5G should be US$40-60. There's no reason an excellent phone like this should cost any more.
Huawei is planning a US$300 phone in 2020. Huaweireport.com.