What type of birthmark is this & how much would removal cost? (Photo)

You have a linear epidermal nevus. I'd advise either surgical excision and suturing of the lesion, possibly in stages, or shave excision, and electrosurgery of the base. Best to chat with your dermatologist about the best option for you.

Google this, its an epidermal naves. Excision is the cure, but it will leave you with a scar. A simple procedure called a curette coupled with laser can reduce the visibility of this birthmark, however you may need repeated treatments in a few years time to keep it flat. All the best, Dr Davin Lim. Brisbane. Australia.