According to known leaker eXtas1s, the Xbox ROG Ally is targeting a cost between €599 for the ROG Ally White and €899 for the ROG Ally Black. In addition to this, he reports that pre-orders will go live for the handheld console in August and the official release date will be in October.

Microsoft Xbox handheld Ally console release date and details confirmed - Microsoft is coming for its share of the handheld gaming market

The price of the ROG Xbox Ally handheld is reported by eXtas1s to be €599 for the white version and €899 for the black version. The black version, as you're probably aware, is the more powerful "ROG Xbox Ally X" variant.