That price nets you the version with 12GB of RAM and 512GB of storage. If you need even more memory, the SKU with 16GB of RAM sells for an extra $100. One thing to note is that despite the company's press release explicitly mentioning availability in stock, neither Amazon nor B&H agree with that at the moment. So it may take a few more days until that's settled.
You should also be able to find various ROG Phone 3 accessories for sale in the US soon. The ROG Kunai 3 gamepad will cost $149.99, the ROG Clip is $39.99, the Lighting Armor case is $59.99, the TwinView Dock 3 is $329.99, the antibacterial screen protector is $36.99, the Professional Dock is $89.99, and the Mobile Desktop Dock is $229.99.
If you're interested in learning much more about the Asus ROG Phone 3, don't miss our in-depth review of the device.