It isn’t terribly expensive to install what’s called split unit air conditioners. They aren’t a cheap stopgap solution like window units, but if sized properly for the space/insulation level they actually work very well.

Don’t fall prey to the temptation of floor/portable AC units, though; they are terribly inefficient. Both window and split unit AC are significantly more efficient options and with split units you can even get heat pump models which will not only cool, but also heat your home more efficiently than any other heat source.

I’m a big proponent of the AC-plus-ceiling fan method, since you don’t have to use the AC as much to feel quite comfortable.