$400, and then another $80 for the "marker", which does not have replaceable tips like every other company that makes a pen-tablet device. Apple, Wacom, Samsung, etc.
So the opex is about $100/year, plus however often you need to replace the 'pen'. That's hitting $800 TCO for three years.
Or you can buy a previous generation iPad Air and Apple Pencil and get a device that is far more capable, has replacement tips, a stylus that supports pressure and angle, etc.
It baffles me that people start frothing at the mouth about Apple "forcing" people to use iCloud when damn near nothing on the device requires a paid iCloud account and there's pretty decent integration with open standards based systems...
...but the ReMarkable is basically PDF reader without their cloud subscription and HNers just can't shut up about how awesome it is?
Oh, and then there's the shady-as-shit return policy. They basically don't have one...unless you buy the cloud service. Which you have to buy in a minimum 3 month block, and is non-refundable.
Edit: apparently there are replacement tips.