Colored hair spray

Hey all my painty peeps:

I am doing a festival and the event coordinator has asked me if I would also be willing to add hair streaks to my offerings. I was close to a booth at the last festival that I did, and it looked to be hugely popular with the kids (and even some teens and adults, too). So I have come to my all knowing and always helpful forum friends to give me a little guidance.
I am intending on using the colored sprays ( I have looked into the chalk thing and it just looks way tooooo messy to deal with), but my questions are how to price it. Do I go by hair length, how many streaks they want. Full head color vs. only streaks?? I am lost on this concept because there are so many ways to do it. What are good price points to offer? I should have sent someone over to the other booth that I saw to ask prices but I didn't because at the time, I had no intention of doing it.

Thanks for any/all help!!!     

I haven’t done it but it would really depend on how much you can get the cans for. Base the prices like you do the face painting - maybe $2 per streak? Keep shaking the can as you spray it.

OOOOOHHHH, price per streak sounds like a good plan. Love it!!!! I am surfing the web to find a good product at a good price. I don't really want to go with the absolute best right from the start because if it is a dud, I will have wasted too much money.
I know on the website it states a 3 oz can does so many streaks vs so many full heads, blah blah but I would rather hear it from someone on here that has actual experience with them to guide me on how much I may need and how many heads/streaks a can will do. If I see it's going to be popular, I will get more and possibly get a better product.
Would it work to do something like girls vs boys hair like
Boys: half head- $5 full head $7 or $2 per streak
Girls: tips only - $5 5 streaks $7 or $2 per streak

That actually sounds fine. Try Dollar Tree if you have one close to you. Pretty sure I've seen it there and everything is $1. So maybe get 10 bottles to test it out.

Maybe for boys offer a mohawk price instead of a streak. 
Like $4. Maybe?

Cheap color spray comes off like cheap face paint.
Be Wild by Jerome Russell is a good brand. It is a bit pricey, but if you can find a deal/wholesale--a spritz of glitter (either spray or poof) ups it nicely.

I wold also look in to the color intensity on darker hair. You may need to use more for brunette vs blonde.

Obviously, pricing depends largely on what your market will bear, but having said that, I can't imagine paying $2 for somebody to spray one streak of Halloween hairspray on my kid's head :/ Of course, when you're in the moment and the kids are begging, things change, but I think it's much more clever to market your prices like you mentioned above: half/full head. I would also stipulate half head (2-4 streaks) or full head (5-7 streaks), something along those lines.

Another fun addition you can offer is hair stenciliing. Smaller print stencils (cheetah print, stars, etc...) work best in my experience, just hold them in place & spray. I actually think it makes the process a lot neater, and it's great to use on kids with very short hair wear a streak would end up looking more like a series of dots.

Good Luck!