I have had used a water cooler before ... and I bought a portable AC - 9,000 BTU.
The water cooler is cheap and nasty, it will cool you if facing direct at you with ice ...the problem is you have to clean them every few weeks or you will get mould build up in the honeycomb filter at the back. I gave mine away in the end.
Now the Portable AC was fine, it was about 7,000-8,000 baht if I remember, it worked well, cooled a 30sqm room down to early 20's ...21-24c ...