You never buy one ESP.
I’m fairly sure there is a law against that.
But if I’m wrong, it makes no sense to only buy one. You always find new places to put them.
Or you accidentally break one, like I did a few weeks ago.
I had just finished everything and it was screwed in to place, and something happened and I needed to reboot the device.
I couldn’t reach the other end of the USB so I pulled out the micro USB side and the connector broke off.
I could grab a new one and flash it and it was up and running again.
Sure, you could run down the street and buy a new one for the price of, I don’t know the price where you are but it’s about four/five times the normal price here.