check out Color Blaze.  They have color powder on their website for less than Amazon prices.
wholesalecolorpowder.com

We do a combo of both liquid and powder dye, the powder is from chameleon colors on amazon, each runner gets a pack and they are about a dollar each.  Then we use the dye from Americolor, get the .75 ounce paste dye and mix with one gallon of water, you’ll get amazing color that so far has not  caused an issue coming off clothing or skin.  Don’t pay a company, they take so much of your profit.  We bought ten tank sprayers and have 3 stations and with an out and back course they will pass by each station twice for a total of 6 chances to get color.  

Hi all. Anyone can give advice on a color run where we only have 3 color stations? Technically not a 5k but a shorter run. How much powder do we get.? We have pre k thru 2nd doing a dash, followed by 3rd thru 5th with parents and siblings. Thanks!

Hi, I'm thinking about a color run fundraiser at our elementary school as well. How did yours turn out 4 years ago?

Hi! I know this is an old thread but hoping someone might be able to help! We are hosting our first color run but are required (by our school and insurance) to do a liquid color run--a "color splash" rather than using color powder. Has anyone else done this? Any tips? I am trying to determine how many sprayers we need at each station, how much liquid color, etc. I would love any feedback, words of wisdom, and ideas from folks who have done this before. Thanks so much!

go to www.wholesalecolorpowder.com. They sell the powder and lots of great information on how to organize a fundraiser