When I first saw these at the shows and they were being sold for £300 plus I thought it would be a good idea but was not prepared to pay that much for an evaporative cooler.
So being a "man with a shed" and a passion for saving a bit of money when you can, I decided I will set and make one, this I did using a couple of computer fans a small 12 V waterpump and a filter unit - stick it in a plastic storage box and yes I have a device that worked well - I tested by using twin digital thermometers, one on the input side and one on the output side - and yes there was a drop in moving air temperature of approximately 5 to 8° C dependent on humidity.
So when we've been in hot dry places and having it placed on the table with the air going towards you it does have a cooling effect.
For information the ones that sell here for over £300 actually come from Australia and my sister has one out there in Perth where she paid about £150 for it - I did call the company and they said they would not send to the UK.
