Wait. Some prices are decreasing but not entirely.
Cheapest 1080 I could find:
PCPartPicker part list:
https://pcpartpicker.com/list/cXZBD8
Price breakdown by merchant: https://pcpartpicker.com/list/cXZBD8/by_merchant/
Video Card: Gigabyte - GeForce GTX 1080 8GB G1 Gaming Video Card ($619.99 @ Newegg Business)
Total: $619.99
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-04-16 07:45 EDT-0400
Just for the record, ^ above card was going for 579 today morning, very close to MSRP. Its stock was bought out pretty quick and it is now 619.