Hello! I couldn't find an updated guide on Hair Colors Basilmarket and Gamerbewbs so I made my own with the help of Omnipotence.
Note that as of this current patch (v160) changing your hair color in Edelstein with VIP or REG will not work. You will still have the coupon and no change. I tried it there three different times with both coupons -______-
I submitted the same guide/image to Basil Wiki a few days ago but as you can see it's still not up. Might do a VIP/REG guide here in the future.