Adding misters-systems to your outdoor landscaping can reduce the temperature from 5 to 35 degrees using a fan water mister.
As an example, I've seen a patio at 105 degrees be reduced to 70 degrees simply because of misters.
You can get whatever your money can afford, however as with any other thing, you get what you pay for. Outdoor misting systems range from 30 PSI to 1000 PSI.
If you have hard water it helps to run the water through a softwater system so the nozzles won't plug up with hard water deposits
Misters work best without wind, which will blow the water away. Also, wind will evaporate the water quicker, so it's more efficient to run them when there's no wind. If you live in the south misters are especially nice because they cool a patio remarkably well.
Backyard water features