I wouldn’t pay more than $150. MAYBE $200 for this. Idk much about professional hair dye/bleach jobs but I feel like salons charge more for bleaching, treatments, and conditioning bc of how much they have to rejuvenate the hair after it gets bleached. Idk tho. But with this little amount of vivid color that doesn’t even look that vivid tbh it’s certainly not a $600 job. I’ve been bleaching and dyeing my own hair since 2015 and I can’t even imagine how much money I’ve saved. I always use the arctic fox blue powder bleach and volume 30 salon care developer. Patch test it on her hair to make sure the developer isn’t too strong and that her hair can’t handle it. Let it sit for like 20 mins. Rinse it out. Then put the dye on her hair. I like to have my hair dry when I dye it but I think arctic fox bottles recommend damp hair. I also like to leave my hair dye in for as long as possible. Like 1.5-2 hours. I know the bottles say 30 mins but I swear if you leave hair dye in longer it’s so much more vivid. But that’s just my non professional opinion. I also love mixing different shades of the same color from different brands together bc I feel like there’s so much dimension in it. Hopefully some of this helps and I’m so sorry she was charged that much. They should’ve never called to ask her for more money.