Danielle Keasling, a celebrity hairstylist, says, “Mermaid hair can cost anywhere from $100 all the way up to $1000 on average in salons, depending on the process. In order to lay in these fantasy tones, you need to pre-lighten the hair most of the time. This is a separate process that needs to happen in order to get the vibrancy of the fashion tones. However, if you’re naturally blonde, most of the time, pre lightening won’t be needed.”