It's not gonna be hot forever; get your shop/cabin/small home ready for winter.
The Williams 3144030 Forsaire is a 31,400 BTU electric counterflow wall furnace designed for spaces without gas hookups.
It retails for roughly $1,180 to $1,270, requires 208-240V power, takes up under a square foot of floor space, and uses a top intake/bottom output blower.
$500 OBO