Leon Speakers Tonecase is the first thing that comes to mind.  They can make it any color you want and also several hardwood finishes.  In-wall is not really what it's designed for, but could probably be adapted or if you call them they might be able to offer some ideas for your installation.

[Link: leonspeakers.com]

Don't know if they have a product yet for the new Play 5 that just started shipping.