With the price of lumber lately, I can see how that might be a good option. I've got a few projects lined up that I've put off until lumber prices come down, which seem to be happening finally. I'll probably start on them once it cools down a bit. My shop isn't very well insulated and it's been like an oven in there lately.
Do you have a back door to the shop? If so, you could make a frame like I did out of 2” square steel tube with casters and a shelf on which I put a 220V window AC unit. When I want to use it, I open the back door and roll the frame into place, and it fits the opening quite closely. I put hardy board on the outside with a plywood interior, and I sandwiched some sheet foam insulation between the two layers. My shop is mostly uninsulated, though I did put a layer of insulation on the inside of the west-facing OH door. The AC does a good job keeping the shop cool up to the low 90s. Here’s a pic, and yes, that’s a doggy door for my four-legged friends who want to keep me company