Check this one out! What a great idea, especially the ability to synchronize the beat across a group. How about 75 of them for a concert band? Or 20 for a jazz band? Maybe they would cut a deal for large orders like that. I’d ask them, if you’ve got the money. Or even four or five for quartet/quintet groups.
Learn more at their site.
The Practice of Practice 
What about the Peterson Bodybeat Sync ?
https://www.petersontuners.com/products/bodybeatsync/
Thanks, Mita. This whole piece of tech is new to me. I might have to test/review these. I’m unfamiliar with all of them! Cheers, Jon.