This ESP32 comes with a battery holder at the back to provide power using a 18650 battery.
Scroll down to find the ESP32 at different stores and find the best price.
Ebay.com
Shrsl.com
Aliexpress.com
$10.99
1 new
from $10.99
as of May 22, 2019 3:32 pm
£11.90
1 new
from £11.90
1 used from £8.64
as of May 22, 2019 3:32 pm
Amazon.co.uk