Edit: I've been informed that PCPer saying the module "I wouldn't be surprised to see that this FPGA alone makes up $500 of the final price point of these new displays, let alone the costly DDR4 memory" is speculation alone. The module might have been cheaper, but I can't confirm any of that. For now, we're going by PCPer's word.
NVIDIA is set to raise the bar so high on enthusiast gaming that it will be years before AMD can catch up, with their new 27-inch 4K 144Hz HDR G-Sync displays right around the corner. But why is there such a high cost behind them? That would be thanks to a new G-Sync module.
Inside of the new ASUS and Acer 4K 144Hz HDR G-Sync gaming panels is a revised NVIDIA G-Sync module that costs $500 on its own, yes... $500 on its own. The ASUS ROG Swift PG27UQ and Acer Predator X27 monitors have a $500 premium on them because of the new NVIDIA G-Sync module, but it's for good reason - running 3840 x 2160 at 144FPS is mind blowing. It's almost unbelievable that they're here all of the sudden, because driving that many pixels isn't easy.
Inside of the new ASUS ROG Swift PG27UQ is an Intel Altera Arria 10 GX 480 FPGA module with 3GB of DDR4-2400MHz RAM, and costs $2000 on its own. NVIDIA is buying them in bulk for the new ASUS and Acer 4K 144Hz HDR G-Sync displays, so they are paying $500 or so per G-Sync module.
The ASUS ROG Swift PG27UQ costs $1999 on its own, so NVIDIA scoring the G-Sync modules on the cheap helps with the overall price.