Ceiling Speakers

I know the very topic precludes anything any of us would consider hi-end sound.  But my neighbor is putting a great room onto his house and is asking me for recommendations as to in-ceiling (i.e., flush mounted) speakers.  So far I have succeeded in pulling him away from Bose, but am having trouble pushing him toward something good.  The feedback on these looks favorable, and I appreciate the design principles:  https://rslspeakers.com/c34e-ceiling-speaker/  

If you have heard anything reasonably priced (let's say $300 or less per speaker) that sounds good, please respond.

Thanks!