I got one from Argos for about £280 this time last summer for my mum's treatment room that she works from and it was an absolute life saver. Definitely would have had to cancel clients otherwise as it got so hot at times.
She's get a sliding sash window, so I positioned it next to the window, and mounted the hot air extractor to a the bottom of the window opening and closed it to keep it in place. It wasn't an air tight seal, but worked well and was easy for her to remove at the end of each day to lock the window back up.
A little noisy, but not overly distractingly so. Well worth the money as it cooled very effectively and really took the edge off the heat making it comfortable on the extreme days.