Get yourself one of these. A bit noisy but powerful enough that it creates enough breeze to make you feel like youre on a brisk walk down at the seafront
I have both an Air Cooler and Portable Air Con Unit
Air Coolers are great when it starts to get warmer, but they really struggle with the hot temperatures, unless you change the water to cold water and lots of ice every couple of hours (crushed ice works best)
For the price I'd recommend an Air Con unit then buy a tumble dryer hose from a DIY store. They're not as rigid as the hose that comes with the Air Con so it makes it easy to pull the window right down so you do not have to seal it up.
We've got an Air cooler on in the kitchen at the moment and it's 28c in there, our lounge is 27c with one on, Bedroom is 28c but will cool down to 20c in about an hour when I pop the air con on.
Amazon is your best bet for an Air Cooler. The cheap ones are just as good as the expensive ones.