I'd like to make a wig for my friend.

My best friend has lost all her hair and I I would really like to help her. I didn't know her when she was going through all this, and I haven't really asked her what happened because I dont want to bring back bad memories. I started growing my hair hoping that this would be enough to make a wig for her. My hair is 54 cm long from my scalp all the way to the tips, I have never dyed my hair and I dont have dead ends so I would say my hair is healthy. I would like to know about the process and how much that would cost as I am a student and I am kind of struggling. Also, I don't really know how to tell her cause I don't want to offend her in any way. Could you please give me some advice on how to approach a matter like this?