I wouldn't ever buy it off Amazon. Direct or from approved vendors that dint have a habit of allowing open box returns. Don't know what some people can rig into a returned piece of electronic crypto equipment
In many instances, I'm willing to cover the upfront efficiency cost because I love bitcoin. But also because I can then explain how this little heater I have is also earning some sats in a very efficient manner. Just don't ask how much I paid for the little heater 😉