Wasserstein Home [wasserstein-home.com] has Wasserstein Ultra Lightweight Elite Headstrap & 5000mah Battery Pack for Oculus Quest 2 on sale $39.99 w/ promo code WASSERSTEINWELCOME5. Shipping is free.
I obtained one among these within the mail a couple of days in the past. Seems fairly good thus far.
Target [target.com] & Home Depot [homedepot.com], & Amazon [amazon.com] all had it for $59.99. Found it for much less direct from the producer.