I assume this is a vendor placing a fictitious price in a yet to be released product. Otherwise, Microsoft is crazy. Their phones aren't bad but they cannot compete against the quality of Apple's ecosystem. Thus, they have to compete on price.
Considering that DQXI is a Unreal 4 game, it seems that Nintendo already secured support from Epic, which means not only tha NX is reasonable powerful but also it will be easier to receive ports from third party publishers.
It doesn't matter how big is the market for mac gaming. Once Square-Enix announced the mac version, the minimum a costumer should expect is the game to run well if the computer met the game's requirements. It seems S-E screwed twice with the same game. I would be worried to purchase any of their games in anything but a console.